Five Palestinians convicted in Pakistan of the 1986 hijacking of a US plane, in which 22 people were killed, have gone to court to block any attempt by the United States to extradite them.
The move comes after a sixth member of the group, Mr Zayd Hassan Safarini, was transferred to the US over the weekend, where he is to be charged with murder.
Two of the people killed in the hijacking of the Pan Am passenger jet in Karachi were US citizens.
The five Palestinians are still being held in a jail in Islamabad despite completing their sentences for the hijacking. Court sources said the Palestinians had sent a petition to the Lahore High Court from their jail.
US president Mr George W Bush yesterday cited Safarini's extradition as progress in his "war on terrorism".
Court sources quoted the five men as saying they feared they would be handed over to the FBI because an Bureau team had recently visited them in jail and taken their pictures and fingerprints.
They were originally sentenced to death by a Pakistani court but their sentences were commuted to 25-year life terms which they have completed in 15 years because of remissions.
They have not been released because they were not recognized as Palestinian nationals by the Palestinian Authority's mission in Islamabad having entered Pakistan with Jordanian or Syrian passports.