Washington, March 18 (DPA) A key Al Qaeda operative believed to have been involved in a December attack on a US base in Afghanistan that left seven CIA employees dead has been killed, a US official said Wednesday.

Hussein al-Yemeni, in his late 20s or early 30s, died last week in North Waziristan, a remote tribal area in Pakistan near the Afghan border, the counterterrorism official confirmed.

The Central Intelligence Agency (CIA) is known to carry out airstrikes in the border regions using pilotless drones, though the spy agency has not publicly acknowledged the use of missile-armed unmanned aerial vehicles armed in Pakistan.

'Al-Yemeni would be the latest victory in a systematic campaign that has pounded Al Qaeda and its allies, depriving them of leaders, plotters and fighters,' the official said.

Al-Yemeni is believed to have established contacts across a broad spectrum of Al Qaeda's network including on the Arabian peninsula, as well as in Afghanistan and Pakistan, said the official, who requested anonymity. He is suspected of serving as a conduit for raising money and recruiting, but specialised in bombs for suicide attacks, the official said.

Al-Yemeni is thought to have played a key role in the Dec 30 attack on a US base in Afghanistan's Khost province.

The suicide bombing was reportedly carried out by a Jordanian who had been recruited by his government as a double agent to provide intelligence on Al Qaeda and Taliban activities.

The bomber, Humam Khalil Abu-Mulal al-Balawi, had apparently duped Jordanian intelligence into believing he was a double agent after being arrested, but had been working for Al Qaeda all along.

Western officials later said the bomber had contacted his Jordanian handler and said he needed to meet urgently with the CIA team at the base. At the meeting, he detonated an explosive vest, killing the CIA employees and the Jordanian handler.

The Taliban claimed responsibility for the attack.

Meanwhile, CIA director Leon Panetta said in an interview with the Washington Post that intensified efforts along the Pakistan-Afghan border against Al Qaeda have pushed Osama bin Laden and his deputies further into hiding.

'Those operations are seriously disrupting Al Qaeda,' Panetta said. 'It's pretty clear from all the intelligence we are getting that they are having a very difficult time putting together any kind of command and control, that they are scrambling. And that we really do have them on the run.'

Panetta said that Al Qaeda's desperation is shown in a recently intercepted message from a top operative urging bin Laden to rescue the group and provide more leadership.

He characterised the stepped up efforts as 'the most aggressive operation that CIA has been involved in our history'.