BAGHDAD // A massive suicide blast hit Baghdad yesterday, killing about 30 people, a bloody reminder of the dangers still facing the country. It happened as the US military announced plans to withdraw 12,000 troops from the country. The troop scale-back, which will take six months, is the start of a complete US military pullout. The US president, Barack Obama, has pledged to bring home all combat troops by Aug 31 2010. A contingent of about 35,000 to 50,000 troops will stay after this date to train and advise the Iraqi military. There are currently 140,000 troops deployed in Iraq. In 2007, at the height of the US offensive known as the "surge", the number peaked at 160,000. The increase is credited with breaking the back of the Shiite militias, Sunni insurgents and al Qa'eda fighters who brought Iraq to the brink of civil war. In November last year, George W Bush, the former US president, signed an agreement with Iraqi officials to withdraw troops from towns and cities by June 30 and from the whole country by the end of 2011. Despite a number of security improvements in the past couple of years, the bomb blast, which targeted police recruits at Baghdad's main police academy, underlines the dangers facing Iraq's fledgling security forces. The bomb was the deadliest in the capital for almost a month. Rumours surrounded the circumstances of the latest blast, initial reports suggesting a suicide bomber, perhaps riding a motorcycle, detonated a vest full of explosives among potential police recruits. According to the Associated Press, two medical officials and a police officer in the area put the death toll at 30, with 60 injured. A police official at the interior ministry placed the figure at 28 killed and 57 wounded. The withdrawal of troops was confirmed by US and Iraqi officials on the day of the blast. "We have agreed that a total of 12,000 US troops will be withdrawn by the end of September 2009," Ali Dabbagh, a government spokesman, told a press conference. "Iraq's armed forces are under construction. "We do not consider the Iraqi security forces are ready. Iraqi forces need to be equipped and trained," he added. He indicated that all foreign troops should have left the country by 2011. He said: "By 2011 they will be able to stand on their own. We are confident of the fact that the security agreement will be respected." It was also confirmed that 4,000 British troops would withdraw from Iraq by July 2009. It is believed about 100 troops from the United Kingdom will remain in the country in an advisory role. The US troop announcement involves the equivalent of two of the 14 combat brigades in the country. They include troops from the 82nd Airborne, Marines and 4th Brigade. An F-16 fighter jet squadron will also be pulled out and not replaced. "We will not leave any seams with regard to security," Major Gen David Perkins told the press conference. "We know how to do this. This is not the first time we have done this." The suicide attack, which happened only hours before yesterday's announcement, shows that despite rapid gains in security the situation remains volatile. The blast follows a deadly attack on Thursday in which a car bomb detonated in an animal market in the town of Hillah, 100km south of Baghdad. The blast killed 13 people. Although neither attack has yet been claimed suspicion has fallen on al Qa'eda in Iraq and other Sunni insurgent groups. talbone@thenational.ae With additional reporting by Agence France-Presse