RAWALPINDI, Nov 24: The US government has sought extradition of three Pakistanis accused of killing four Americans in a terrorist attack in Karachi, an official source Dawn on Monday.

The source said the Federal Bureau of Investigation (FBI) wanted to investigate the three Pakistanis, who had been exonerated by an anti-terrorism court. The four US citizens, who were working for Union Texas oil company in Karachi, were killed on November 12, 1997.

Shortly after the incident, the three Pakistanis, identified as Mohammad Faisal, Kashif David and Wasim Tunda, were taken into custody and tried in the ATC, which acquitted them after the prosecution failed to substantiate the charges.

The source said the FBI had also interrogated these three Pakistanis in July 1998 but failed to establish any link with the killing at that time. However, the US government has demanded their extradition and detailed report on the case, saying the FBI wanted to interrogate them again.