DERA ISMAIL KHAN (Reuters) - A U.S. drone airstrike in Afghanistan has killed a Pakistani militant accused of involvement in a deadly attack on a bus carrying Sri Lanka’s cricket team in 2009, Pakistani security sources and Islamist militants said.

Islamist militants are increasingly basing themselves in Afghanistan after an army crackdown in Pakistan, officials in the country say.

The U.S. unmanned aircraft struck a car carrying Qari Mohammad Yasin, also known as Ustad Aslam, on Sunday in the southwestern Afghan province of Paktika bordering Pakistan, Pakistani intelligence sources said.

The attack killed Yasin, who specialized in training suicide bombers, and three other militants, added the officials, who declined to be identified as they are not allowed to talk to the media.

There was no immediate comment from U.S. military officials in Afghanistan.

Pakistan’s Counter-Terrorism Department had offered a bounty of 2 million rupees ($19,000) for Yasin, saying he was involved in the 2009 bus attack in the northeastern city of Lahore, allegedly organized by militant group Lashkar-e-Jhangvi.

Confirmation of the death came from Ali bin Sufyan, spokesman for a Lashkar-e-Jhangvi offshoot, Al Alami, which has cooperated with militant group Islamic State in the past.

The group carried out a bomb attack against Pakistan’s military in the southwestern province of Baluchistan as “revenge”, he added, without giving details.

The attack on the Sri Lankan team bus led to Pakistan’s exclusion from the role of hosting major international tours.

At least 10 gunmen fired on the bus with rifles, grenades and rockets, wounding six players and a British coach, and killing eight Pakistanis.

Since then, Pakistan has been forced to play most of its ‘home’ games in the United Arab Emirates.

Pakistani police last year also said they killed three other militants involved in the 2009 attack.