Suicide car bombers carried out two deadly attacks in Baghdad Thursday, killing 11 people as the Iraqi president met with Britain's prime minister in London ahead of Iraq's constitutional referendum.

An American soldier also was killed Thursday in combat operations in northern Baghdad.

Fear of spiraling violence before next week's referendum was one of the topics President Jalal Talabani and Prime Minister Tony Blair were expected to discuss.

At a joint news conference after their meeting, Mr. Talabani said the presence of American and British troops in Iraq is absolutely vital, and that no timetable for their departure has been set.

For his part, Mr. Blair said new, more dangerous explosives are being used in Iraq, and there are unproven suspicions they are coming from Iran or its Lebanese ally, Hezbollah. Those charges were quickly denied by Iranian and Hezbollah officials.

Some information for this report provided by AP and AFP.