ISLAMABAD, Feb 25: Security forces on the trail of Osama bin Laden were on Wednesday questioning nearly two dozen Al Qaeda and Taliban suspects captured in a dramatic operation near the Afghan border.

The suspects were arrested on Tuesday after hundreds of Pakistani troops backed by helicopter gunships swooped on a town in the semi-autonomous South Waziristan tribal region.

But officials refused to comment on a report in a Pakistani newspaper that a son of Ayman al-Zawahiri, a top Osama's lieutenant, was among the detainees. The paper, quoting diplomatic sources, said Khalid al-Zawahiri was handed over to US custody soon after his arrest and flown out of Pakistan.

"The identities and nationalities of the suspects would be known when interrogation is over," a security official said. The arrest, if confirmed, would be a major boost to US-led efforts to track down Osama.

A US military spokesman in Kabul said they did not have any information on arrests from the operation carried out by Pakistani authorities in the tribal region.

"We don't have any reports coming out of Pakistan in reference to who they picked up, at least I haven't seen anything yet," Lt-Col Matt Beevers said. "Clearly coalition forces support the Pakistani army's efforts in Fata. They continue to do an outstanding job."

Mr Beevers said the Americans did not know where Osama was hiding but said the "sands in this guy's hourglass.... are running out." Pakistan had dismissed speculation that Tuesday's border operation targeted Osama, following reports that his location had been pinpointed on a different stretch of the Pakistan-Afghanistan border.

Intelligence officials revealed that foreign women were among the detainees but declined to release any more details. "Among the men how many are foreigners I cannot comment," military spokesman Maj-Gen Shaukat Sultan told AFP.

Troops rounded up around two dozen people and seized weapons, ammunition, audio cassettes, documents and passports during Tuesday's operation in the Zeralitta region of South Waziristan.