BAGHDAD (Reuters) -- Suicide bombers have killed at least 19 people in Iraq in separate attacks in Baghdad and the northern city of Kirkuk, security officials said, underscoring the fragility of Iraq's security gains.
In the latest attack, a suicide bomber struck at a crowded market in the south Baghdad district of Doura, killing 12 people and wounding 25 others, police said, adding that three U.S. soldiers were also killed.
The U.S. military could not immediately confirm this.
Earlier on May 21, a bomber triggered a vest packed with explosives as Sunni anti-insurgent militiamen queued to be paid in Kirkuk, killing seven people, the army and police said.
The blasts come hours after a car bomb killed 40 civilians and wounded 82 others in Baghdad's poor, mostly Shi'ite district of Shula late on May 20, police said, revising higher earlier figures of 35 killed and 72 wounded.
Iraqi officials have lauded security gains in Iraq in the last year, but a rash of bombings in April made it the deadliest month for civilians since November.
The recent attacks raise questions about whether Iraq can avoid sliding back into increasing violence as the Iraqi military prepares to take greater security responsibility and U.S. troops prepare for a full withdrawal by the end of 2011.