MOSCOW, AUG. 20 -- Eleven Siberian convicts, armed with machine guns and explosives and saying they wanted political asylum, hijacked a Soviet passenger jet Sunday, forced it to fly to Karachi and surrendered there today to Pakistani authorities.

The Aeroflot jet, carrying 29 other passengers and a crew of nine, landed in Karachi with only about 10 minutes of fuel left -- "a near crash position," according to one Pakistani airport official.

The plane, which had been scheduled to transport the prisoners from Neryungri, site of a convict labor camp, to Yakutsk, in eastern Siberia, where they were to transferred to another camp, circled Karachi airport for some time and was allowed to land only after Soviet Premier Nikolai Ryzhkov asked Pakistani authorities to intervene.

Hundreds of police and troops with armored cars and tanks surrounded the plane, and the 11 hijackers surrendered two hours later. Officials said the passengers and crew appeared to have been unhurt in the hijacking, the 13th in the last three months in the Soviet Union.

Soviet Deputy Premier Ivan Shilov said that such a large number of prisoners ordinarily would not be transported together but that a shortage of domestic flights "even for ordinary passengers" had made it necessary.

Shortly after takeoff from Neryungri Sunday, the prisoners took over the plane, threatened to blow it up and demanded to return to the airport. There, they allowed 41 women and children to leave the plane. The aircraft then flew southward to Krasnoyarsk, where authorities allowed it to be refueled, and then to Tashkent in the Soviet Central Asian republic of Uzbekistan, where the crew was replaced.

After all-night negotiations between the hijackers and officials in Tashkent, the prisoners agreed to free an undetermined number of the remaining passengers and the original crew members, while Soviet authorities refueled the aircraft and allowed it to fly to Karachi.

Soviet officials have been dismayed by the recent rash of hijackings here and have emphasized in public reports that Western officials have cooperated in the arrest and extradition of all hijackers. Finnish authorities today extradited 21-year-old Mikhail Varfolomeyev who recently hijacked a flight from the Estonian capital, Tallinn, to Lvov in the western Ukraine and ordered the crew to fly to Helsinki.