Two gunmen hijacked a Soviet Aeroflot airliner on a domestic flight today, forced it to land in Helsinki and then demanded to fly on to Stolkholm, Sweden, Finnish national television said.

The television report said the gunmen's nationality was unknown, but both spoke Russian. They held about 70 passengers in th plane, identified as a medium-ranged, twin-jet Tupolev 134.

The gunmen allowed the crew of five to leave the aircraft shortly after it landed the network said.

The plane's destination and point of origin in the Soviet Union were not known.

Finnish officials confirmed that the hijackers wanted to fly on to Sweden, but they said they would refuse to refuel the plane until the seven children aboard were set free.

The Swedish government was considering whether to allow the plane to fly to Stockholm, a question complicated by the fact that ministers from the Organization of Petroleum Exporting Countries are scheduled to begin arriving at Stockholm's Arlanda Airport tonight. An OPEC conference begins at a Swedish town on Tuesday.

It was the third hijacking around the world in a week.

Palestinian hijackers surrendered to Syrian authorities in Damascus tonight after a flight from Kuwait in an airliner they had commandered earlier in Beirut.

Five hijackers forced a Chilean domestic flight to fly to Lima, Peru, last week. They have been granted political asylum in Cuba.

Successful hijackings of Soviet planes have been rare. The last one occurred May 26, when a Soviet mechanic, Vasily Sosnovsky, 37, seized a twin-engine AN-24 aircraft on a Soviet domestic flight from Riga to Daugavpils, Latvia, and ordered the pilot to fly to Stockholm.

The Swedish government decided June 9 that Sosnovsky should stand trial in Sweden. Soviet authorities had demanded extradition.