PESHAWAR, Pakistan (Reuters) - A suspected U.S. drone strike on a training camp in an isolated part of Afghanistan’s eastern province of Kunar on Wednesday killed more than 20 Pakistani Taliban preparing to launch suicide attacks in Pakistan, officials said.

Two Pakistani intelligence officials said the attack, carried out in a village called Saresha Sultan Shah, killed at least two senior figures in the movement, besides someone believed to be a trainer of suicide bombers.

The Pakistani Taliban, also known as Tehrik-i Taliban Pakistan or TTP, is separate from the Afghan Taliban and combines a number of groups that fight the government of Pakistan. The U.S. State Department has put it on a list of foreign terrorist organizations.

Last month, a suspected U.S. drone strike on the Pakistani side of the border killed the deputy leader of the TTP, which has been waging a campaign of bombings and other attacks on Pakistani forces.

The Pakistani intelligence officials said Wednesday’s drone strike in Kunar, an undeveloped and thickly forested province on the two countries’ border, took place during a visit by senior TTP figures prior to sending the militants into Pakistan.

They said it killed Gul Mohammad, a TTP leader in Bajaur Agency on the Afghan border, and Qari Yaseen, whom officials described as a “master trainer of suicide bombers”. A son of TTP leader Fazlullah Khorasani was also killed, they added.

Sources in the Pakistani Taliban confirmed the strike had killed more than a dozen of their members but said Fazlullah Khorasani, who was visiting the training camp at the time of the attack, had not himself been killed.

A spokesman of the NATO-led Resolute Support mission and U.S. forces in Afghanistan headquarters in the capital, Kabul, did not confirm the report.

“We were not aware of this report and have no additional information to offer,” he said in an emailed statement.

Last year, the CIA requested increased authorities to conduct covert drone strikes against militant targets in Afghanistan.

Provincial officials in Kunar confirmed a drone strike had been carried out, but did not say what the target had been.

Afghanistan and Pakistan accuse each other of allowing militant groups to shelter in remote frontier regions to prepare cross-border attacks. U.S. officials have also accused Pakistan of not doing enough to crack down on such groups operating on its side of the border.

Relations between Washington and Islamabad have become increasingly strained over the issue and the United States this year suspended about $2 billion in assistance to Pakistan.