A car bomb has left at least 28 people dead and another 62 wounded in the southern Iraqi city of Basra.

Police said the explosion took place in the main market place in the old part of the port city.

The blast came just days after Iraqi Prime Minister Nouri Maliki visited the city and declared a state of emergency to try to impose calm.

The premier has vowed to crack down on gangs in the city who he said were threatening the country's oil exports.

A large number of people were shopping in the market at the time of the explosion, police said.

Pools of blood and the charred remains of several vehicles were seen at the site of the blast where hundreds of onlookers gathered to watch the rescue efforts.

It was one of the deadliest attacks to hit the oil-rich city since the start of the US-led invasion in three years ago.

Diplomat killed

The latest bloodshed came just hours after a Russian diplomat was killed and four others kidnapped in the Iraqi capital, Baghdad.

Officials said gunmen used cars to block a road in the western Mansour district before opening fire on the Russian diplomatic vehicle.

Witnesses said the victims had been out buying food. Their white sports utility vehicle was shown on TV with shattered windows.

Mansour houses a number of embassies and has been the scene of attacks on other diplomats.

In other violence

· Iraqi police say they have found eight severed heads on a roadside near the town of Baquba, 60km (35 miles) north-east of Baghdad - one of the dead is identified as a local Sunni preacher

· Militants open fire and throw grenades at a checkpoint in Baquba killing seven policemen and wounding another 10 people

· Police find four bodies in different areas of Baghdad, all showing signs of torture.

Photo Caption

An Iraqi policeman picking through the wreckage