Osama Bin Laden's son Saad has begun playing a prominent role in his father's al-Qaeda network since the group went into hiding following the US campaign in Afghanistan, US intelligence officials say.

The attack in Tunisia killed 19 people, mostly German tourists

Saad - one of Bin Laden's eldest children - has become more active in financing and other logistical support for several al-Qaeda operations, the officials said.

They also suspect he was involved in the bombing of a synagogue in Tunisia earlier this year, which both the US and Germany believe to be the first al-Qaeda attack since 11 September.

However the officials said they did not believe Saad - who is thought to be in his early twenties - had taken charge of the group.

Like his father, he is thought to be in Pakistan or Afghanistan.

There has been much speculation about the fate of Osama Bin Laden, with US officials admitting they do not know whether he is alive or dead.

Rumours rife

Indian Defence Minister George Fernandes further fuelled speculation on Monday by saying he had information that Osama Bin Laden was living in Pakistan.

"We have information the man is around and he is somewhere in Pakistan. We had it from unimpeachable sources," Mr Fernandes said in an interview with the UK's Channel Four News television.

His comments drew a furious denial from Pakistan.

Mr Fernandes was "talking through his hat", said a spokesman for President Pervez Musharraf.

Spokesman Rashid Qureshi dismissed his comments as typical Indian propaganda meant to discredit Pakistan.

He said if there had been any evidence of the whereabouts of Osama Bin Laden, the US would have been the first to know.

The US blames Bin Laden and al-Qaeda for the 11 September attacks which killed about 3,000 people.