Pakistan is the one country suspected more than others as a place of refuge for al-Qaeda leaders, with its historical ties to islamic militant groups and leaders of the former Taliban regime.

However, it continues to deny suggestions that some key figures have taken refuge there.

Nearby countries such as Iran and Iraq were said to have become the new hosts for Al-Qaeda, though there's little information to prove that point.

A senior government official says: "Al-Qaeda leaders would not have headed towards Pakistan in the first place, knowing that we are so closely allied to the US now."

"Why would you want to travel to a country with not only a hostile government but also a public which is largely not supportive," he says, referring to the largely muted public response to General Pervez Musharraf's ban on five Islamic militant groups, as an example of how the mainstream public remains distrustful of al-Qaeda.

But western officials say Pakistan had many previous ties to the Taliban and the al-Qaeda leaders, so many would have used the country as a transit point after leaving Afghanistan.

Senior Pakistani officials deny claims that Mr bin Laden, who is thought to suffer from a kidney ailment, travelled to Pakistan last year for treatment. But concerns over such past ties continue to be a matter of discussion among individuals with connections inside Afghanistan.

"Under five years of Taliban rule, devastated Afghanistan went from worse to much worse," says a Pakistani businessman who claims to have regularly supplied daily use supplies to senior Afghan figures under the Taliban.

"For smaller needs like cough and cold, Afghan leaders could stay in Afghanistan. But for anything more major like surgery or indeed dialysis as everybody talks about Osama bin Laden, they all travelled to Pakistan."

But western officials say the chances of prominent al-Qaeda leaders continuing to remain within Afghanistan can not be ruled out, especially with continuing uncertainty over the future of the interim Afghan government, led by Hamid Karzai.

Mr Karzai's inauguration in December was followed insurgencies in the west and the south-east of Afghanistan. While US troops pursued Taliban and al-Qaeda members, concerns over Mr Karzai's failure to prevent fresh defiance triggered worries that key members of the two groups might still be hiding inside Afghanistan, waiting for fresh opportunity to wage a war against the new regime.

"If Karzai is failing to come to grips with this situation in its entirety, there are different ways of reading that situation," says a senior western >official. "One way to read that is to say this is all part of the teething problems. But the other way to read that is perhaps to say, there are still anti-West and anti-Karzai factions, possibly backed by (Afghanistan's) former leaders, who are creating such trouble".