At least 12 people, many of them children, have been killed in bomb attacks while they were playing football in west Baghdad, police say.
Two blasts hit a makeshift pitch on waste ground in a mainly Shia district. About a dozen other people were hurt.
Police say the bombs had been buried in the middle of the football pitch.
The attack came hours after Iraq's president said Iraqi forces would take over the security of the entire country from US-led forces by the end of 2006.
President Jalal Talabani told a news conference the transfer would happen gradually but would be completed before the new year.
Iraq has been hit by repeated bomb attacks despite attempts by the government to improve security.
More than 50 people died on Tuesday across the country.
They included 23 soldiers whose bus was hit by a roadside bomb north of Baghdad, and 14 people killed in a suicide car bombing in centre of the capital.
Attacks on police patrols in the north and north-east also killed 12, and a British soldier was killed in Basra.
Police say those killed and injured in Wednesday's attack on the football game were aged between nine and 20.
Two mortar shells hit another Shia area, killing three young people, some of whom were also playing football, police said.
Meanwhile the US military said a soldier and a marine had been killed in the western province of al-Anbar, AFP news agency reported.
The soldier, from the 1st Armored Division based in Ramadi, was killed in "enemy action" on Tuesday, while the marine died in action on Wednesday, the agency said.