Several assailants broke into a house in Pakistan's eastern city of Lahore in the pre-dawn hours on Saturday, overcame security guards and kidnapped a U.S. man identified as an international development expert, police said.

In Washington, a State Department spokeswoman identified the man as Warren Weinstein.

Weinstein has been identified as working for J.E. Austin & Associates, an Arlington, Virginia-based consulting firm, on a development project in lawless tribal areas where Pakistani troops have been battling Islamist insurgents for years.

"Six to eight people broke into his house at around 3:30 a.m., when security guards on duty were making preparation for fasting," police official Tajamal Hussain told Reuters, referring to the Ramadan fast observed by Muslims.

"Two of the assailants came from the front gate while about six others used the back door. They tortured the guards and then took the American with them."

A security official familiar with the incident said the gunmen forced the man's driver to knock on his bedroom door. When the man opened it, they took him.

Hussain said the victim, in his 60s, had been living in Pakistan for five to six years. He mostly lived in Islamabad but had been traveling to Lahore.

The security official said there had been no claim of responsibility.

The State Department spokeswoman, Joann Moore, said, "We are working with local authorities on the investigation." Moore added that members of Weinstein's family were receiving support from the U.S. consulate in Lahore.

Well-known in development circles

A biography of Weinstein on his consulting firm's website said he has a doctorate in international law and economics, is a Fulbright Scholar with 25 years of experience in international development projects and is well known among donor agencies, development banks and private sector groups working with emerging economies. The Fulbright Program is run by the U.S. State Department.

"Currently, Dr. Weinstein is serving as Chief of party for JAA (J.E. Austin Associates) on the Pakistan Initiative for Strategic Development and Competitiveness," the firm's website said.

Later Saturday, Weinstein's biography was removed from the website.

A representative of J.E. Austin could not be immediately reached for comment at the firm's office in Arlington.

The firm is handling the development initiative as a contractor for the U.S. Agency for International Development, the main foreign aid arm of the U.S. government, according to a USAID report on the project.

Anti-U.S. sentiment runs high in Pakistan. Prickly ties between Islamabad and Washington hit a low point after the May 2 killing of al Qaeda chief Osama bin Laden in an attack that Pakistan termed a breach of its sovereignty.

Kidnapping for ransom is relatively common in Pakistan, although foreigners are not often targets. Militants also occasionally take foreigners hostage.

Pakistani Taliban, linked to al Qaeda, have claimed responsibility for kidnapping a Swiss couple in July in the volatile southwestern province of Baluchistan.

They said the couple could be freed in exchange for a Pakistani woman serving a jail term in the United States for shooting FBI agents and U.S. soldiers in Afghanistan.

Eight Pakistani employees of a U.S.-based aid organization, American Refugee Committee (ARC), were kidnapped in Baluchistan last month.