At least 14 people have been killed in violence across Iraq.

A mortar attack in the Dora neighbourhood of Baghdad has left four people dead and ten injured.

Three mortar rounds hit the mostly Sunni area, which has been the site of daily bombings and shootings in recent weeks.

Earlier, six oil workers were killed when the bus they were travelling in was hit by a roadside bomb in Baghdad's southern al-Dora district. 12 others were wounded in the blast.

The bomb blast came a day after al-Qaeda in Iraq vowed to carry out large-scale attacks that would 'shake the enemy' after the killing of its leader, Abu Musab al-Zarqawi.

In the north of the country, two civilian contractors were shot dead while on their way to work in Tikrit.

And in the city of Amara, three gunmen ambushed and shot dead a former Ba'ath party member. The southern city was tense after clashes yesterday between British troops and Mehdi militia which left five Iraqis dead and one British soldier wounded.

A police officer was also killed by gunmen between Tikrit and Ouja, 180km north of Baghdad.

Bush holding talks on Iraq situation

The US President, George W Bush, is opening two days of discussions at Camp David today for what his advisors say is a crucial re-assessment of the war in Iraq.

Senior diplomats, military officials and key presidential aides will assemble and confer via telephone linkups with members of the new government in Baghdad.

The meeting is expected to review the US position in Iraq, including some discussion about the gradual withdrawal of US troops from the country.