Pakistan has continued to express its grave concern about the situation in the besieged city of Kunduz, in northern Afghanistan.

A government spokesman, General Rashid Qureshi, said the United Nations and the American-led coalition should do whatever they could to prevent a human tragedy there.

However, the authorities in Islamabad are reluctant to comment on the widely reported involvement of volunteers from Pakistan fighting with the Taleban in Kunduz.

General Qureshi said they did not know if any Pakistanis were involved, how many there were or who they were.

Pakistani volunteers

But one eyewitness who has just left Kunduz said foreign fighters, mostly Pakistanis, Arabs and Chechens, were in the city terrorising the population.

Observers say there could be several hundred Pakistanis in Kunduz, but it is not known which groups they come from.

Some of the Pakistanis who went into Afghanistan are highly trained militants, who have been fighting in Kashmir.

But others are untrained volunteers from areas close to Afghanistan, some of whom came from the radical Islamic group Tanzim Nifazshariat-i-Mohammed, which says many of its members are missing.

Pakistan has stressed that if any Taleban or their supporters in Kunduz surrender, they should be treated as prisoners-of-war and not executed.

General Qureshi said Pakistan was not looking for favours or for the Pakistanis to be released.

It did not want any fighters to go in to support its old ally the Taleban, although it was unable to stop them from crossing the porous border.

Many of those returning have been detained for possessing unlicensed weapons or travelling without valid documents.