Among the victims was Kazi Aref Ahmed, leader of the Jatiyo Samajtantrik Dal or JSD, a small left-wing party in the governing coalition, who became a prominent national figure as a result of his role in Bangladesh's war of independence.

David Chazan: Kazi Aref Ahmed was a national figure

Mr Ahmed was shot while addressing a rally in the western district of Kushtia, speaking out against political violence.

Bullets riddled his body as he finished his speech and was about to leave the rostrum. His colleagues, all from Kushtia, died while trying to save him, one police officer said.

From his home, Mr Ahmed's body was taken to Dhaka's Shaheed Minar (Martyrs' Memorial) where Prime Minister Sheikh Hasina offered flowers to the coffin.

The body was then taken to the nearby Eidgah ground for funeral prayers.

Vow to end violence

During the ceremony, Shekh Hasina said she was determined to stamp out the political violence which has plagued southern Bangladesh.

Nearly 1,000 people were killed last year in clashes between rival armed groups, most of which claim allegiance to radical socialism but which in practice, political analysts say, operate like outlaw bands, indulging in extortion and racketeering.

The funeral was also attended by several cabinet ministers, including Home Minister Rafiqul Islam, who told the mourners that he had asked police to launch a massive hunt to arrest the perpetrators.

"The killers will be booked," he said.

"His death was a great loss to our nation," said Commerce and Industry Minister Tofael Ahmed.

"Those who opposed independence and democracy might have a hand in the killing," the minister said, adding that the truth would be revealed when an investigation was completed.

Followers and police suspected the killers belonged to "underground communist groups", blamed for the shooting deaths of 700 people in 1998 and 100 so far this year.

The BBC correspondent in Dhaka, David Chazan, says that although ministers were shocked at the killing, the prime minister's appeal for an end to violence may fall on deaf ears given accusations that her supporters have been involved in clashes with opposition sympathisers.

More killings feared

Earlier Bangladesh police said they feared more political killings, predicting a backlash by protesters.

"It seems the Kushtia killings will provoke retaliation and may open the doors for further killings," said a Kushtia official.

Tuesday's deaths were the latest in a series in Kushtia and neighbouring areas, known as a hub for communist outlaws. Police efforts to catch the outlaws have failed so far.