One of Al Qaeda's top strategists and a prominent figure in the network, Abu Yahya al-Libi, may have been killed in a drone strike in north-west Pakistan, the country's intelligence officials say.

If his death is confirmed it would be the biggest blow to Al Qaeda since United States special forces killed Osama bin Laden in a secret raid in Pakistan in May 2011.

US sources said al-Libi, a Libyan cleric with a degree in chemistry who has survived previous drone attacks, was a target of a strike early on Monday (local time) in the North Waziristan tribal region, home to some of the world's most notorious militant groups.

Some US officials describe al-Libi, whose real name is Mohamed Hassan Qaid, as number two to leader Ayman al Zawahri, the former Egyptian doctor who took over Al Qaeda after bin Laden's death.

Pakistani intelligence officials said they believe al-Libi may have been among seven foreign militants killed in the strike.

One of the officials said Pakistani authorities had intercepted telephone chatter about al-Libi, an Al Qaeda theologian and expert on new media, whose escape from a US-run prison in Afghanistan in 2005 made him famous in the terrorist network's circles.

"We intercepted some conversations between militants. They were talking about the death of a 'sheikh'," one of the Pakistani intelligence officials said.

"They did not name this person but we have checked with our sources in the area and believe they are referring to al-Libi."

However, a militant commander in North Waziristan closely associated with foreign fighters said he had not been killed.

"This is not the first time claims have been made about his death," he said.

"The Americans are suffering heavy losses in Afghanistan, so they have resorted to making false claims."

It can take months to confirm whether drone strikes have killed an Islamist militant leader because the area of the attack is often sealed off by the Taliban in the lawless north-west of Pakistan.

Burials are quick in order to hide casualties and identities.

If a drone strike did kill al-Libi, it would bolster the American argument that drones are a highly effective weapon against militants.

The Pakistan government says that while the CIA-run pilotless drone campaign has some advantages, it fuels anti-American sentiment in the country and is counterproductive because of collateral damage.

Reuters