A son of the leader of a major Taliban faction attacking Western forces in Afghanistan has been killed in a missile strike by a U.S. drone in Pakistan, security officials said on Friday.

The killing of the son of veteran Afghan guerrilla commander Jalaluddin Haqqani came days after the arrest of the Afghan Taliban's top military strategist, Mullah Abdul Ghani Baradar, in a joint Pakistani-U.S. operation in the city of Karachi.

A pilotless U.S. drone fired two missiles into a Haqqani network compound on Thursday in Pakistan's North Waziristan ethnic Pashtun tribal region on the Afghan border, killing three people.

Mohammad Haqqani, a son of Jalaluddin Haqqani whose network is linked to al Qaeda and has carried out several high-profile attacks in Afghanistan, was among the dead, Pakistani security officials said.

But another son of the elder Haqqani, Sirajuddin Haqqani, is a much more high-profile target of the U.S. drones.

Mohammad Haqqani is a younger brother of Sirajuddin. He (Mohammad) was killed in the attack, a security official who declined to be identified told Reuters.

Jalaluddin Haqqani, who is in his 70s, has passed on the leadership of his militant faction to Sirajuddin.

U.S. forces in Afghanistan describe Sirajuddin as one of their biggest enemies and the United States has posted a bounty of up to $5 million for him.

Thursday's drone strike was in Dandi Darpakhel village near North Waziristan's main town of Miranshah where many members of Haqqani's extended family have been living since the U.S.-backed Afghan jihad, or holy war, against Soviet forces in the 1980s.

Sirajuddin Haqqani was known to visit the village but another Pakistani intelligence agency official said he was not there at the time of the attack.

Residents and government officials also confirmed the death of Mohammad Haqqani.

U.S. drones have targeted the village several times and 23 people, many of the members of the Haqqani family, were killed in a strike there in September 2008.

HIGH-WATER MARK

Jalaluddin Haqqani has had close links with Pakistani intelligence, notably the military's main Inter-Services Intelligence (ISI) agency.

U.S. ally Pakistan officially objects to the drone strikes, saying they are a violation of its sovereignty and fuel anti-U.S. feeling which complicates Pakistan's efforts against militancy.

But at least some strikes are carried out with the consent of Islamabad, in particular those on Pakistani Taliban militants fighting the state.

U.S. envoy to Afghanistan and Pakistan Richard Holbrooke on Thursday hailed the arrest of Baradar, the Afghan Taliban's number two man, as a high-water mark for Pakistani-U.S. collaboration.

But Interior Minster Rehman Malik suggested Baradar might not be handed over to the United States. Asked by a reporter about the fate of Afghans arrested in Pakistan, Malik said they would be investigated for any crime in Pakistan.

If found innocent, they would be returned to their country and not the United States, he said.

Pakistani cooperation against militants is a sensitive issue for the government of a country where many people are suspicious of the U.S.-led campaign against militancy.

Despite that, Pakistan has arrested hundreds of al Qaeda members since the September 11 attacks on the United States and handed many of them over to the United States.

The Haqqani faction does not launch attacks in Pakistan but sends fighters across the border into Afghanistan from its stronghold in lawless North Waziristan.

Separately, two pro-Taliban militants suspected of involvement in several high-profiles attacks in Pakistan were killed in a shootout with police in the central city of Faisalabad after they refused to surrender, police said.

In the southwestern province of Baluchistan, unidentified gunmen kidnapped four Pakistani aid workers employed by a Western relief agency.

Taliban operate in the gas-rich province as well as separatists not linked to the Taliban who have been waging a low-level insurgency for decades.

Separatists kidnapped an American working for the United Nations in Baluchistan last year and held him for more than two months before releasing him.

(Additional reporting by Alamgir Bitani and Gul Yousafzai; Editing by Robert Birsel and Raju Gopalakrishnan)