President Bush and senior Iraqi Shi'ite politician Abdel Aziz al-Hakim of the Supreme Iraqi Islamic Council met privately in Washington on Tuesday.

White House spokeswoman Dana Perino said they discussed the improving overall situation in Iraq and other political and security issues.

In Baghdad Tuesday, Iraqi officials say U.S. troops killed as many as seven Iraqi civilians, including a child, in two separate shootings.

Iraqi security officials say as many as four people were killed when U.S. troops opened fire on a minibus as it advanced toward a roadblock in northern Baghdad. A U.S. military spokesman says the driver failed to heed a warning shot.

In a separate incident, the U.S. military said American troops shot at a car speeding toward a checkpoint in Baiji Monday, killing two men and a child. A spokesman said the military regrets any civilian casualties in the fight against terrorists in Iraq.

In Diyala province on Tuesday, the U.S. military says a female suicide bomber wounded five Iraqis and seven U.S. soldiers when she blew herself up in the city of Baquba.

Also in Diyala, Iraqi police say a suicide bomber disguised as a shepherd killed at least six people at a police headquarters.

In other news, the military says two U.S. soldiers were killed in an explosion during combat operations Tuesday in northern Salaheddin province.

And, a delegation of Sunni religious leaders met with Iraq's most respected Shi'ite cleric, Grand Ayatollah Ali al-Sistani, in the Shi'ite holy city of Najaf. A Sunni cleric says Sistani called for unity and an end to sectarian violence.