KABUL, May 1: A Nato-led offensive in a restive southern Afghanistan district killed up to 56 militants, including some Pakistani nationals, on its first day, an Afghan commander said on Tuesday.

“We've killed up to 56 Taliban, including lots of Pakistanis,” General Moheydin Ghori from the Afghan army told AFP by telephone from the area.

The bodies of the dead had been left at the site in Helmand province's Sangin Valley, he said, and a handful of Pakistani fighters had also been arrested.

The Nato-led International Security Assistance Force (Isaf) had earlier said the operation, launched on Monday, had

killed “a significant number of insurgents.” Some 2,000 Nato-led and Afghan troops are involved in the new sweep, called Operation Silicon. “We're advancing through Sangin very successfully and the Taliban have been defeated,” Ghori said.

The sweep is part of the Operation Achilles, a major offensive launched on March 4 in Helmand, a province plagued by violence. Achilles is the biggest Isaf operation this year, involving some 5,500 soldiers.

Local and international forces are trying to “create security conditions in the Sangin Valley so that meaningful reconstruction and development can occur,” said an Isaf spokesman, who declined to be identified.

Separately, four insurgents were killed in an air raid in response to an attack by a dozen militants late Monday on the administration office of eastern Khost province's Spera district, the US-led coalition said.

Also in Khost, 11 suspected Taliban militants with links to Osama bin Laden's Al Qaeda network were seized in a “joint operation” by Afghan and Isaf troops, provincial governor Arsala Jamal told AFP.

The new claims of success against the Taliban came as police in the western province of Herat said at least 30 civilians died in clashes at the weekend which the coalition said killed 136 Taliban.

Hundreds of people had demonstrated in the Shindand district of the western province of Herat on Monday, after coalition and Afghan operations there on Friday and Sunday, insisting civilians were among the victims.

Herat police chief Mohammad Shafiq Fazli told AFP an investigation had found that “there were at least 30 civilians, including women and children, among those killed in Shindand's fighting.” As government and UN teams were sent to the area to investigate the claims, a spokesman for the US Central Command said it had received no reports of civilian casualties in the fighting.

“Every precaution is taken to prevent injury to Afghan civilians during both battles, and no civilian casualties were reported,” said Major David Small. There were two battles in the Herat fighting.

In the eastern province of Nangarhar, meanwhile, 500 students protested against US military action after six people were killed on Sunday.

The demonstrators, who burned an effigy of US President George W. Bush, said all six were civilians. The coalition has said four were militants and that a woman and a teenager were killed in crossfire.

In other violence linked to the growing Taliban insurgency, Afghan police in the province of Paktia escaped a suicide attack unhurt, the provincial governor said.

The attacker tried to jump onto a police vehicle before blowing himself up but instead “became the victim of his ill-attempts,” Governor Rahmatullah Rahmat told AFP.