Pakistan's President, General Pervez Musharraf, has said it is "impossible" that Osama Bin Laden could be hiding in Pakistan.

If Bin Laden was alive, he obviously would be moving with a large entourage of local people

Pervez Musharraf

"I doubt he is alive, and if he is alive he cannot be in Pakistan," he told a news conference on Monday.

Speculation is rife that, during the American-led assault on Afghanistan, Bin Laden may have slipped across the border into Pakistan's tribal areas.

At the weekend, the Pakistani Government issued advertisements asking for help in capturing Bin Laden and other senior leaders of the al-Qaeda network.

The organisation is blamed for the 11 September attacks on New York and Washington.

'Living openly'

"If he was alive, he obviously would be moving with a large entourage of local people and therefore they would like to have a safe haven, a large area for themselves," General Musharraf said.

"He cannot be hiding in one small corner of Pakistan in the border areas, and his remaining there without being found is also impossible."

There is a whole network, a whole grid of safe houses, of cars, of logistics, of support for these militants inside Pakistan

Pakistani author Ahmed Rashid

But correspondents say there is some scepticism over General Musharraf's comments, given that a group of al-Qaeda fighters last week killed 10 soldiers and militiamen near the border with Afghanistan.

And in April, US forces arrested Abu Zubaydah - an alleged key al-Qaeda recruiter - inside Pakistan.

Leading Pakistani author Ahmed Rashid has told the BBC that significant numbers of al-Qaeda and Taleban members are not only living openly in the country, but they also have the support of the people.

He said: "Clearly there is a whole network, a whole grid of safe houses, of cars, of logistics, of support for these militants inside Pakistan. The regime has done absolutely nothing about tackling this issue."

Popular support for Bin Laden is high in Pakistan

He added: "Most of the Taleban cabinet is living in Peshawar, untouched.

"They go shopping, they meet people, they have dinner parties, they invite people into their homes.

"Many of them are living in Quetta and many of the other Taleban and al-Qaeda are living in Punjab and in Karachi."

Off-limits

Last month, Pakistani troops went for the first time into remote mountainous regions near the Afghan border that have traditionally been left to tribal rule.

Pakistan's tribal areas, set up after partition from India, stretch for hundreds of miles along the border with Afghanistan.

Although officially part of Pakistan, they have their own laws and customs and the rule of the authorities does not apply there.

A big military deployment is under way in parts of the tribal areas, indicating the government's desire to clear the area of suspected militants.