Pakistani media follow a senior police officer at outside the house of an abducted American citizen in Lahore, Pakistan on Saturday. – Photo by AP

LAHORE: Pakistani police said Thursday they would carry out lie-detector tests on security guards and a driver of a US aid expert kidnapped from his home in the eastern city of Lahore.

Warren Weinstein, 70, country director for US-based consultancy J.E. Austin Associates, was snatched at gunpoint before dawn on Saturday.

Police have so far drawn a blank over the kidnapping which saw Weinstein - who has been in Pakistan for seven years - struck on the head with a pistol and driven off.

“We have decided to conduct lie-detector tests on the security guards and the driver to verify their statements given to investigators,” senior police official Atif Hayat told AFP.

“From today, we will start their screening. We are also interrogating the security company officials responsible for his security,” Hayat said.

“We are questioning all those who served at his office in the past,” he added.

The American had lived in Model Town, an upmarket Lahore neighbourhood once home to former prime minister Nawaz Sharif, for five or six years, using the ground floor as an office and the first floor as a residence.

Weinstein had been due to return to the United States on Monday after concluding his contract on private-sector development and economic growth in Pakistan, a frontline state in the war on terror where anti-US feeling is rife.

There has been no claim of responsibility and the most officers have been able to establish is that he was targeted because of his nationality.

Washington this month revised its travel warning, saying that Americans throughout Pakistan have been kidnapped for ransom or for personal reasons.

On July 1, a Swiss couple were seized while on holiday in Balochistan, a sparsely populated southwestern province bordering Iran and Afghanistan which is known for separatist violence and Taliban activity.

Wali-ur Rehman, deputy chief of Pakistan's umbrella Taliban faction, later claimed responsibility for that kidnapping.

In February 2009, an American UN official was also kidnapped and held for two months in Balochistan.