J.E. Warner, an American national working in Pakistan on a development project, was abducted from his Islamabad residence on Saturday.

According to police, six to eight abductors broke into Warner's house early morning and took him with them.

"Some six to eight people broke into his house at around 3:30 a.m., when security guards on duty were making preparation for fasting," Reuters quoted police official Tajamal Hussain as saying.

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

Warner, in his 60s, had been living in Pakistan for the past five years. He mostly lived in Islamabad but had been traveling to Lahore, Hussain told Reuters.

All the guards and servants have been taken into custody for questioning, Xinhua quoted Senior Superintendent Police Investigation, Abdul Razaq Cheema as saying.

Until now, no group has claimed responsibility for the kidnapping.

The U.S. Embassy in Karachi, in May, had issued an advisory for the U.S. citizens in Pakistan saying that they should take measures for their safety and security at all times as the U.S. Consulate in Karachi had received information regarding a threat against American citizens and interests.

Beginning with the kidnapping and beheading of American journalist Daniel Pearl of the Wall Street Journal in Karachi in February 2002, Americans have been targets of abduction and torture in Pakistan.

According to the U.S. Bureau of Consular Affairs, since 2007, several U.S. citizens throughout Pakistan have been kidnapped for ransom or for personal reasons. Kidnappings for ransom are particularly common in KP and Balochistan Provinces.

In 2008, one Iranian and two Afghan diplomats, two Chinese engineers, and a Polish engineer were kidnapped in KP Province. In February 2009, a U.S. citizen UNHCR official was kidnapped in Balochistan. In 2010, a U.S. citizen child was kidnapped in Karachi. Kidnappings of Pakistanis also increased dramatically across the country, usually for ransom.