Iraqi construction workers in the southern city of Karbala have uncovered a mass grave less than a kilometre from one of Shia Islam's holiest sites.

Iraqi police announced yesterday that about 30 bodies were contained in the mass grave.

It is believed they are among the victims of Saddam's vicious suppression of the 1991 uprising by the Shia majority in southern Iraq at the end of that year's Gulf War.

Some 300 possible mass graves have been reported since Saddam was overthrown by the US-led invasion in April 2003, many in southern Shia areas of the country and in Kurdish areas of the north.

But potential evidence has been taken by relatives who have converged on the sites in search of their loved ones.

Saddam is currently on trial on charges of crimes against humanity.

Yesterday's find by the workers who were laying a sewage pipe, 500m from the shrine of Imam Hussein, comes as the Shia-led government is keen to publicise the atrocities of Saddam's 23-year dictatorship.

The Sunni-Shia rift has widened after the elections despite the participation by the Sunni minority, who had earlier boycotted a poll for an interim parliament.

The US-led occupiers have ignored appeals from the Sunni community which is demanding a rerun of the December 15 poll.

With final results not expected for another week, the preliminary tally shows that the Shia have taken a commanding lead in the elections for the 275-seat parliament.

In Baghdad, the Shia Islamist Alliance took 59 per cent of the vote, compared with 19 for its nearest Sunni rivals and 14 per cent for former prime minister Ayad Allawi's secular coalition.

More than 10,000 people marched through Baghdad yesterday to protest against what they said was a flawed vote and demanding a national unity government that would give more power to Sunni Arabs and secular Shia.

Some carried pictures of Mr Allawi, a Shia who led the non-sectarian list in the election.

Marchers chanted: "No Sunnis, no Shia, yes for national unity."

The continuing sectarian violence has maintained the pressure on foreign forces in Iraq.

Bulgaria and Ukraine yesterday announced that their troops had completed a pullout from Iraq.

However, in a policy U-turn, Poland yesterday signalled that it planned to keep its troops in Iraq for another year.

The new Polish prime minister, Kazimierz Marcinkiewicz, asked President Lech Kaczynski to extend the mission, which has proved unpopular in Poland and has cost the lives of 17 Polish soldiers.

Polish troop levels would be cut in March to 900 from about 1500 in March under the plan which is expected to be approved by the president who is from the same conservative party as Mr Marcinkiewicz.

The previous left-wing government had pledged to pull out the troops at the beginning of next year.

"This is a very difficult decision, but we take into consideration the fact that the mandate of UN stabilisation forces has been extended to the whole of 2006 and, secondly, strong requests of Iraqi authorities that we stay there," Mr Marcinkiewicz said.

The Polish troops, which have been a combat force, would focus in the future on advising and training Iraqi security forces.

Britain and the US, which makes up the bulk of coalition forces with more than 130,000 soldiers in Iraq, insist that their forces will only withdraw when Iraqi forces are able to take care of security.

But the Iraqi police have been infiltrated by insurgents and there are fears that the Shia-dominated security forces may be engaged in revenge attacks on Sunni prisoners.

At least two dozen people were killed over the weekend in post-election violence that has targeted foreign troops and Iraqi forces working with the occupiers.

Clashes between gunmen and Iraqi police in Baghdad yesterday killed two police and two bystanders, and wounded five people.

South of Baghdad, a roadside bomb targeting a police patrol killed two officers and wounded two.

In another attack, gunmen southeast of Kirkuk, in the Kurdish area of northern Iraq, killed one police officer and wounded two.

The US military announced that two US pilots died in a helicopter crash in western Baghdad on Monday night.

However, no hostile fire was involved.