A US drone strike killed the deputy chief of the Pakistani Taliban Wednesday in the country's lawless tribal northwest, officials said, dealing a major blow to the militant network.

Waliur Rehman, the number two in the Tehreek-e-Taliban Pakistan (TTP) faction, died along with at least five others when an unmanned US drone fired two missiles on a house in North Waziristan district early Wednesday.

Pakistani security sources told AFP that Rehman, who had a $5 million US government bounty on his head, was the target of the strike, which came a week after US President Barack Obama outlined new more restrictive guidelines on drone use. It was the first known drone strike since that announcement.

Officials in several towns, as well as tribal and intelligence sources, confirmed Rehman's death in the attack in Chashma village near Miranshah, the main town in North Waziristan district, a stronghold of Taliban and Al-Qaeda-linked militants.

The United States refused to confirm that it had killed Rehman, despite Obama's promise of more transparency on the drone war.

"We are not in a position to confirm the reports of Waliur Rehman's death," White House spokesman Jay Carney said. But he added: "If those reports were true, or prove to be true, it's worth noting that his demise would deprive the TTP of its second-in-command and chief military strategist."

Pakistani security officials said the others killed in the attack were TTP cadres, including two local-level commanders. There were no initial reports of civilian casualties.

Washington had accused Rehman of organising attacks against US and NATO forces in Afghanistan and also wanted him in connection with a suicide attack on an American base in Afghanistan in 2009 that killed seven CIA agents.

Rehman had been a key figure in the TTP since its inception in 2007 and was second-in-command of the national hierarchy behind Hakimullah Mehsud, as well as leading the group in South Waziristan.

The loss of such a senior leader will come as a blow to the TTP, which has waged a bloody campaign of bombings against the Pakistani state in recent years, though Rehman was seen as more moderate -- relatively -- than Mehsud.

Rehman came from a religious background and set up his own seminary in his native South Waziristan, teaching children before turning to militancy.

Pakistan's incoming prime minister Nawaz Sharif has supported the idea of peace talks with the Taliban and sources said there had been the impression that Rehman could have had a role to play in the process.

Washington says drone strikes have been an effective tool in wiping out important Taliban and Al-Qaeda figures in the militant-infested badlands along the Afghan border.

But they have been unpopular in Pakistan, where the government publicly denounces them as illegal and a violation of sovereignty.

Obama last week defended the legality of the CIA-run strikes, which began in Pakistan in 2004 and became more frequent during his presidency. But he outlined new rules for their use.

The guidelines say drone strikes can only be used to prevent imminent attacks, when the capture of a suspect is not feasible and if there is a "near certainty" that civilians will not be killed.

Carney would not confirm Wednesday whether the attack on Rehman satisfied the new criteria.

The attack was the first since Pakistan's May 11 general election, won by Sharif's Pakistan Muslim League-N.

Sharif, due to assume office on June 5, has called the drone strikes a "challenge" to his country's sovereignty and said Washington must take Pakistani concerns seriously.

According to Britain's Bureau of Investigative Journalism, CIA drone attacks targeting suspected Al-Qaeda and Taliban militants in Pakistan have killed up to 3,587 people since 2004, including as many as 884 civilians.

The frequency of drone strikes in Pakistan has tailed off in recent months, the last coming on April 17.

On Sunday US Secretary of State John Kerry said this was because the tactic had "been so successful in rooting out Al-Qaeda in Pakistan" and was only used after targets were confirmed "at the highest levels".