"The hospital in Diwaniyah received the governor and police chief, and three other corpses from their security detail," said Doctor Hamid Gaati, head of the health directorate in Diwaniyah, 200 kilometres (120 miles) south of Baghdad.

Speaking on condition of anonymity because he was not authorised to release the information, a senior security official in Diwaniyah said they were killed in a muliple bomb attack on their conoy.

"More than 10 IEDs (roadside bombs) targeted a convoy of the governor and the chief of police on their way back from Afak to the centre of the city, killing the governor of Diwaniyah and the chief of police," said the official.

The governor, Khalil Jalil Hamza, and the police chief, Major General Khalid Hassan, had travelled to Akak to attend a funeral, he added.

Iraqi state television said the deputy governor had ordered an indefinite curfew from 7:00 pm (1500 GMT) on Diwaniyah, following the killings in what the channel called an isolated area without security protection.

Diwaniyah has proved a flashpoint for rival Shia factions battling for supremacy in the region, and has regularly witnessed heavy clashes between Shia militiamen and US and Iraqi security forces.