US Marines increased their forces near the southern Afghan city of Kandahar yesterday and intensified air attacks on the last remaining Taliban stronghold in the country.
The Marines fought their first engagement overnight, sending attack helicopters to fire on a convoy of 15 vehicles heading for the desert airstrip they seized in the early hours of Sunday.
However, the Taliban showed no sign of giving up Kandahar vowing to fight the Americans until their last breath.
Thousands of Taliban, with tanks and artillery, and foreign al-Qaeda fighters are believed to be in the city.
The US Attorney General, Mr John Ashcroft, said he believed members of al-Qaeda were in custody.
"We believe we have al-Qaeda membership in custody," Mr Ashcroft said.
However, he said he was not going to release most of the names of those held for security reasons.
The US-held airstrip where 1,000 Marines will be based within days is within striking distance of Kandahar.
Five-hundred marines are today expected at the airstrip, 20 km southwest of Kandahar, to join the 500 who were flown in from ships in the Arabian Sea to secure the airstrip.
AH-1W Cobra helicopter gunships guiding a Navy F-14 strike fighter attacked a Taliban armoured column near Kandahar.
Meanwhile, further details emerged yesterday of the massacre of up to 600 foreign pro-Taliban fighters in a prison fortress in Mazar-e-Sharif.
Northern Alliance forces, helped by US and British advisors, began an attack after a rebellion erupted Sunday in the prison where some 600 foreign pro-Taliban fighters had been brought.
They fired several salvos into the fort where they were detaining mostly Pakistani, Chechen and Arab fighters, including some believed to be linked to bin Laden. They had been brought from Kunduz, the last Taliban bastion in the north which fell on Monday.
"There is no more fighting. But we will wait until tomorrow to enter because we fear that some of the bodies of the Taliban foreigners may be booby-trapped with grenades," a commander said.
One alliance official said 300 to 400 of the prisoners had been killed while another said "almost all" of the 600 were dead.
Cmdr Nuri said 45 to 50 alliance soldiers died in the fighting. After fierce exchanges of mortar and machine-gun fire and waves of US air strikes in the last three days, alliance forces feared pockets of resistance might remain at the prison fortress.
Evidence is emerging the Northern Alliance reneged on its commitment to detain foreign Taliban fighters in Kunduz. Some fighters faced summary execution in the northern city when it fell to the alliance on Monday.
The Red Cross last night expressed its "grave" concern about the plight of Taliban prisoners in Afghanistan.
A spokeswoman said: "We are concerned about what has happened in the fortress and reports of summary executions in Kunduz are a great concern."
Alliance officials and US media reported a US advisor, possibly a CIA operative, was killed during the rebellion, but this has yet to be confirmed by Washington.
Tribal forces said they were closing in on the southern end of the Taliban domain, around Spin Boldak, amid fresh reports the militia had lost control of the border town.
One report said 5,000 Pashtun tribesmen had taken over the frontier town on the route from Kandahar to Pakistan, from the Taliban and were looting blankets and other goods from humanitarian relief consignments.
Meanwhile, the Pakistan government has issued a 24-hour surveillance alert to prevent people from crossing illegally into Pakistani.
It announced it had stepped up security along its frontier with Afghanistan to prevent bin Laden from slipping into the country. "The border security forces have been put on a 24-hour surveillance alert and tribal leaders have been asked to stop people from crossing illegally," a senior Pakistani government official said.