Pakistan claims to have captured Bin Laden's sons

Two of Osama bin Laden's sons were arrested in southern Afghanistan yesterday in a joint operation by Pakistani and US forces, a minister for Pakistan said last night.

Sanaullah Zehri, the minister in charge of security in the province of Baluchistan, said the men had been picked up near Rabat in the south-west of the country where it borders Pakistan and Iran.

Seven al-Qa'ida men were killed in the operation, he said. There had been reports of US military activity in the area.

The claim met surprise in Washington, with one official at the White House saying: "We think it is wrong." At the Pentagon, two senior officials said that they could not confirm the arrests. Haji Eid Mohammed, the Afghan military commander in Rabat, denied the report. "My people are patrolling with the Americans and for a long time there has been no large American military operation here," he said.

The sons were Saad and Hamza bin Laden, the minister said. Saad, believed to be about 23 and the eldest of Bin Laden's sons, is thought by Western intelligence to be closely tied to al-Qa'ida and is on America's wanted list.

Bin Laden is believed to have at least 23 children by several wives.

The US has stepped up its hunt for the al-Qa'ida leader in recent days. Its forces have been dropping leaflets on the Afghanistan and Pakistan border, offering a $25m (£16m) reward for information leading to his capture.

US special forces were also reported to be in the region investigating information obtained during the interrogation of Khalid Sheikh Mohammed, allegedly the third most senior al-Qa'ida leader.

American intelligence is engaged in an intense drive to establish whether Mohammed has been in touch with Bin Laden and is sifting through documents and computer files seized during his arrest a week ago. Its officials hope this material will point to the whereabouts of Bin Laden.

Few these days give any credence to suggestions that Bin Laden is dead – a view underlined on Thursday when rumours abounded in Washington that the Americans and Pakistanis were closing the net around him.

The Associated Press, citing a Pakistani military source, said yesterday that since Mohammed's arrest, Pakistani and US forces had been searching for Bin Laden and his son, Saad, along a 350-mile stretch of the border from the Pakistani town of Chaman to the Iranian border.

Pakistani intelligence circulated reports to the Western media saying that Mohammed had told his interrogators he met Bin Laden recently. Other officials in Pakistan and the US denied this. The accuracy of these claims is hard to establish because Mohammed may be lying. General Pervez Musharraf, Pakistan's ruler, said Mohammed had given "varying statements" about his contact with Bin Laden.