Islamabad - Unknown gunmen shot dead a US aid worker and his driver in Pakistan's north-west on Wednesday, officials and media reports said.

The attack occurred in an upmarket neighbourhood of Peshawar, the capital of North West Frontier Province, located close to the restive tribal region.

"Assailants lying in ambush opened fire on the US national's car as it drove down an alley in the University Town (area of Peshawar), killing the foreigner and his local driver on the spot," an area police officer said on condition of anonymity.

The vehicle was struck by several bullets, and television footage showed blood spatters and broken glass at the site of the attack.

The police officer said the US citizen was working for FATA Development Programme, which is being run by the United States Agency for International Development.

FATA represents Pakistan's seven tribal districts along the Afghan frontier. The lawless region is considered a hotbed of al-Qaeda and Taliban militants.

Private television channels identified the US national as Stephen Devency, but the identity could not be confirmed independently.

Wes Robertson, a spokesman for the US embassy in Islamabad, only confirmed that "an American citizen and his Pakistani driver were killed in the attack." He, however, did not give details of the US national's identity.

Robertson said the slain American was not a diplomat.

"We are working on some leads but so far there are no witnesses to corroborate the evidence," said Abdul Qadir, a senior police officer.

According to Qadir, officials from the US consulate in Peshawar were coordinating with the law enforcers in the investigations. The victim's body has been handed over to his heirs, he said.

The deadly strike follows an August 26 gun attack on the US consulate's principal officer, Lynne Tracy, in the same locality. Tracy escaped the attack unhurt as she was travelling in an armoured vehicle.

Militant violence has increased in Pakistan's north-west following a surge in US air strikes on suspected Taliban militants in the tribal belt and offensives launched by the government forces to clear the areas of insurgents. (dpa)