LAHORE: An American aid expert kidnapped at gunpoint from his home in the Pakistani city of Lahore was targeted because of his nationality, police said Sunday as they scrambled for leads.

Anti-American tensions are at an all-time high in Pakistan after a covert US raid killed Osama bin Laden on May 2.

The US embassy named the man as Warren Weinstein, who Pakistani police said is a senior official at US-based consultancy J.E. Austin, which works on development projects in the frontline state in the war on al Qaeda.

He was snatched at dawn on Saturday in the wealthy neighbourhood of Model Town, just two days before he was due to return to the United States after five years in the deeply conservative nuclear-armed Muslim country of 167 million.

“One thing has been confirmed - that he is American and that he was kidnapped for this reason,” Atif Hayat, a senior police criminal investigation official told AFP in Lahore.

There had still been no claim of responsibility, he said, and officers were questioning his guards and colleagues, and combing phone records, as part of the search. “So far we have no clue, nor has anyone contacted us,” he said.

Although kidnappings of Westerners are relatively rare in Pakistan, abductions in the country involve both al Qaeda-linked militants and criminals looking for pay-offs.

Lahore is the capital of the eastern province of Punjab and considered one of Pakistan's more liberal cities. Other Westerners abducted in recent years have been snatched in far more volatile parts of the country.

Police described the abductors as Urdu-speakers, so not obviously from the militant flashpoints in the northwest, wearing Western-style shirts and trousers, according to witness testimony from one of Weinstein's guards.

Investigators have been frustrated by a lack of witnesses coming forward to say they saw him being driven off in what kind of vehicle.

Police said eight kidnappers forced their way into the house by offering food to the guards for a traditional pre-dawn meal at 3:30 am (2230 GMT Friday) before beginning the daily Ramadan fast of observant Muslims.

Hayat said the kidnappers tied up, blindfolded and taped over the mouths of the security guards, locked them in a room and then took the driver upstairs to Weinstein's bedroom.

“They did not take away anything from the house except the man,” he said.

Police say Weinstein is around 65 years old, from Maryland and speaks Urdu.

He blended in by wearing traditional Pakistani clothes of baggy trousers, a loose-fitting shirt and a waistcoat, they said.

“This is a high-profile case and two police teams are busy in the investigation,” said Hayat. “There are up to 25 local Pakistani staff working under him and we're also questioning them.

“We are collecting call data of all those working in the office including Weinstein's phone calls,” said Hayat.

Few neighbours seemed to know Weinstein, who police said had lived in Lahore since 2006, working for J.E. Austin Associates, which recently completed a development project in the militant-infested northwestern tribal belt.

One man told AFP on condition of anonymity that he had only seen a foreigner in the street twice in six years.

“I thought it was some NGO office. Not many houses are given on rent in this area,” he said.

Pakistani-US relations are in dire straits, set back seriously by Pakistan's seven-week detention of a CIA contractor who killed two men in Lahore in January and the American operation to kill bin Laden.

US citizen Raymond Davis was eventually released after $2 million in blood money was paid to the families of the dead, but the incident sparked huge anger in Pakistan and raised deep suspicions about covert CIA operations.

Washington last Monday revised a 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 Baluchistan, a sparsely-populated southwestern province bordering Iran and Afghanistan 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 Baluchistan.