President Barack Obama that he felt "confident in moving forward" with the withdrawal.

one protester says of security forces Troops beat demonstrators in Tehran square, sources say Many remain too afraid for their safety to speak  Officials say many foreign nationals arrested in connection with unrest  TEHRAN, Iran (CNN) -- Security forces wielding clubs and firing weapons beat back demonstrators who flocked to a Tehran square Wednesday to continue protests against an election they have denounced as fraudulent, two witnesses said.  Hard-line Iranian students mock British, U.S. and Israeli flags outside the British Embassy in Tehran on Tuesday.   "They were waiting for us," one source said. "They all have guns and riot uniforms. It was like a mouse trap.  "I see many people with broken arms, legs, heads -- blood everywhere -- pepper gas like war," the source said.  The source said security forces beat people like "animals."  Another witnesssaid hundreds of people were chased by security forces and clubbed about a mile from the square. Yet another source, a man who spoke to his wife in the area of the square, recounted what she told him in a phone conversation.  He said she saw security forces shooting and beating people and saw blood on people's clothes and in the streets. The woman said security forces had been carrying butcher knives and batons. They were among the more than half a dozen witnesses who said security forces who outnumbered demonstrators used overwhelming force to crush a planned demonstration in Baharestan Square, in front of the parliament building.  The witnesses said police charged the demonstrators, striking them with batons, beating women and old men, and firing weapons into the air in order to disperse them.  Watch a witness describe the beatings »  The melee extended beyond the square, according to one woman, who said she was traveling toward Baharestan with her friends as evening approached "to express our opposition to these killings these days and demanding freedom.  "But the black-clad police, they stopped everyone," she said. "They emptied buses that were taking people there and let the private cars go on ... and then, all of a sudden, some 500 people with clubs of wood, they came out of the Hedayat Mosque, and they poured into the streets, and they started beating everyone."  People were heard yelling "death to the dictatorship, death to Ahmadinejad, death to Khamanei and death to Basiji," she said. Government-run Press TV gave a starkly different account, saying that about 200 protesters who had gathered in front of the parliament and another group of about 50 people in another nearby square were dispersed by security forces.  "A heavy presence of police prevented violence in the area," Press TV said.  At the nearby Bank of Melli hospital, a person who answered the phone said no one had been admitted as a result of any clashes.  The protests came as President Mahmoud Ahmadinejad met in Tehran with a delegation from Belarus in his first official meeting since the disputed June 12 election triggered widespread unrest. The official results of the election gave the incumbent president a landslide victory, but his challengers have declared that it was rigged and are seeking a new vote.  Ahmadinejad's claim of victory got further support from Ayatollah Ali Khamenei, the supreme leader, who endorsed the results and reiterated Wednesday that the government will not back down. Demonstrators must follow the law, he said. According to official figures, 17 people have been killed in clashes with government forces over the past 11 days. Anti-government demonstrators have taken to the streets in at least four cities outside Tehran.  But CNN has received unconfirmed reports of as many as 150 deaths related to the popular uprising. The government's response to it appears to have hardened in recent days. CNN has received numerous accounts of night-time roundups by government forces of opposition activists and international journalists from their homes.  Some Tehran residents said they were too afraid to talk about the political crisis over the phone to anyone in the United States or Europe. Many protesters debated whether to venture into the streets.  Watch an Ahmadinejad supporter describe the protests »  "I am not going outside my house at all," a 21-year-old college student from Tehran said. "The streets are too dangerous, and just so very busy with police. Ahhhh, when will our lives get back to normal?" At least 69 people have been killed by a bomb blast in the eastern Sadr City area of Baghdad, Iraqi officials say. Police said the device went off in a market place in the predominantly Shia area of the Iraqi capital.  More than 130 people were also reported to have been injured in the blast, one of the worst in Iraq this year.  It comes less than a week before US soldiers pull out of all Iraqi cities, a move the US said would not be affected by a recent surge in violence.  An interior ministry official told the AFP news agency the blast struck the market place at about 1930 I saw cars flying in the air because of the force of the explosion   The official said the bomb was hidden underneath a motorised cart carrying vegetables for sale.   "I heard a boom and saw a ball of fire," said Najim Ali, a 30-year-old father who was injured in the blast.   "I saw cars flying in the air because of the force of the explosion," he was quoted as saying by AFP.   Raad Latif, a local shop owner, said the scene after the blast was "horrific".  He said people ran to help the injured after hearing the explosion but were initially kept back as security forces tried to get emergency vehicles to the scene.  "After a while they came to their senses and allowed us to help as much as we could. The scene was horrific," he told Reuters.   Another witness told the Associated Press news agency he heard a sound like "unbelievable thunder" and was knocked to the ground by "a hurricane".  Market stalls were set on fire and an official told AP that people standing 600m away were hit by shrapnel.  Under an agreement with the Iraqi authorities, most of the 133,000 US troops in Iraq are due to leave the country's cities and towns and withdraw to military bases by 30 June.   US troops are due to withdraw from Iraqi cities by the end of June   Combat operations across Iraq are due to end by September 2010 and all US troops will be out of the country by the end of 2011.   White House spokesman Robert Gibbs said the top US commander in the country, Gen Ray Odierno, had told President Barack Obama that he felt "confident in moving forward" with the withdrawal.   "Gen Odierno has mentioned that we have seen violence greatly decrease even in the past many months from what it was," he said.   Mr Gibbs said Mr Obama had no plans to change the withdrawal arrangements.   The BBC's Jim Muir in Baghdad says the location of the latest blast was significant, as Sadr City has been struck often and provocatively in the past.  The attacks have been attributed to Sunni militants' attempts to provoke sectarian tensions.  Attacks have increased as the US withdrawal approaches   But this tactic has failed since the Shia Mehdi militia, which used to retaliate, was disbanded last year, says our correspondent, and the attacks now only succeed in killing civilians.   The attacks are the latest in a violent week in Iraq.  On Monday, at least 29 people were killed in attacks in Baghdad and elsewhere.  Three people, including a four-year-old child, were killed in the Shaab district of north Baghdad, while a car bomb killed five people in the capital's central Karrada district.  In the largest attack of the year, more than 70 people died in a truck bombing in Kirkuk on Saturday.  But Iraq's Prime Minister Nouri Maliki has said the violence will not delay the withdrawal which, he said, would ultimately be a triumph for the country.  He urged Iraqis: "Don't lose heart if a breach of security occurs here or there."