ISLAMABAD - Pakistan fears the Northern Alliance will take the Afghan capital Kabul to block any major role for Pashtun tribes in a post-Taliban government, but is counting on U.S. pressure to prevent their advance.

Pakistan is a key partner in the U.S.-led coalition punishing the Taliban rulers for sheltering Saudi-born militant Osama bin Laden and his followers.

But it also wants the ethnic Pashtun majority, the source of the Taliban, to get the lion's share in any future government.

Pakistan fears the anti-Taliban alliance, mainly from ethnic minorities in northern and central Afghanistan, will deny a major role to the Pashtuns, who are also found inside Pakistan.

Echoing Pakistani President Pervez Musharraf, U.S. President George Bush and Secretary of State Colin Powell have publicly urged the alliance not to enter Kabul until a broad-based administration is ready to replace the Taliban.

But, emboldened by its rapid capture of about 40 percent of the country, the alliance has threatened to take Kabul without waiting for an interim setup.

"It will cause a lot of concern in Pakistan," Ahmed Rashid, a Pakistani author of a study on the Taliban and an expert on Afghan affairs, told Reuters on Monday.

"It will increase the hostility of Pakistani Pashtuns to General Pervez Musharraf, who are already up in arms because of his policies in support of the (U.S.-led) alliance."

But Riffat Hussain, chairman of the Department of Strategic Studies at Islamabad's main Quaid-i-Azam University, played down the threat, saying the Northern Alliance depended on Washington and could not ignore its will.

U.S. INFLUENCE

"They are engaging in a lot of sabre-rattling and hard posturing," he said about repeated threats towards Kabul from the alliance foreign minister, Abdullah Abdullah.

"They would much rather camp outside Kabul than march in against the advice of the Americans."

"The Americans do have a lot of military clout over the Northern Alliance...(and) I don't think the Americans will let them have their way."

Pakistan hosted almost all mujahideen factions now in the Northern Alliance when they fought the Soviet occupation of Afghanistan in the 1980s and then helped them take Kabul after the collapse of the former Soviet-backed government in 1992.

The relationship turned sour in mid-1990s with the rise of the Taliban, which the alliance says was guided by the Inter-Service Intelligence (ISI) -- Pakistan's main spy outfit.

Pakistan has always denied the link, but recognised the Taliban government in 1997 and was its main ally until Musharraf switched from friend to foe after the September 11 attacks.

Musharraf has predicted Pashtuns will revolt against Taliban leader Mullah Omar, who rejected Pakistani advice to hand over bin Laden, prime suspect in the September attacks.

That has not yet happened. Nor have there been results from moves by exiled King Zahir Shah, who lives in Rome, and his Pakistan-based supporters to provide an interim government.

Rashid said Pakistan should support calling a council of all Afghan factions as soon as possible and throw its weight behind the ex-king.

As alliance forces attacked Taliban frontlines north of Kabul, a Pakistan Foreign Ministry spokesman said "quick moves should be made for a political solution in Afghanistan".

"The Afghan situation cannot be resolved militarily," spokesman Aziz Ahmed Khan told a briefing.

Asked about a demilitarised Kabul, Khan said: "That is the best alternative." Nampa-Reuters