One or more hijackers demanding the "release of all comrades detained in West Germany prisons" seized a Lufthansa airliner with 91 hostages aborad Thursday.

The Boeing 737, hijacked after leaving the Spanish island Mallorca on a flight to Frankfurt, was refueled at Rome before flying to Larnaca airport in Cyprus.

An unknown group issued a statement in Arabic saying it was responsible for the hijacking and linking it to other terrorist acts against West Germany officials and businessmen.

Police at Rome's airport believed at first that they were dealing with a lone hijecker. They said later that analysis of recording of conversations with the plane indicated there might be two hijackers on board.

Alfi Lombardo, of the airport security staff, said a hijacker threatened to blow up the plane at one point when there was a delay after refueling.

A statement is grammatical and concise Arabic delivered to Reuter news service in Beirut said the hitherto unknown Organizations of Strugle Against World Imperialism was responsible for the hijacking.

The statement said the hijacking confirms "the objectives and demands" of the West German Red Army guerrillas who kidnapped West German industrialist Hanns Martin Schleyer Sept. 5.

The kidnapers of Schleyer, have complained in letters to European newspapers that the West German government was stalling on meeting their demands.

The statement demanded the release of imprisoned members of the West German Bander-Meinhof urban guerrilla organization.

The statement attacked the "imperialist-reactionary-Zionist alliance" and referred to the killing of West German banker Juergen Ponto and chief prosecutor Siegfried Buback Ponto, Buback and Schleyer all served "the aims of the neo-Nazis in Bonn and the Zionists in Tel Aviv," the statement said.

Police surrounded the plane on an isolated runaway at Rome's international airport and negotiators tried unsuccessfully to convince the hijacker, armed with a gun, to release the passengers before being allowed to take off.

The pilot of the plane told the control tower at one point in the conversation he would have to take off even if Italian authorities tried to block the plane. Police said the plane took off suddenly, without authorization.

Rome airport sources said eight passengers on the plane were members of a Spanish air crew on their way from Mallorca to Frankfurt. Most of the others were West German vacationers returning from Mallorca, a Lufthansa spokeswoman in Frankfurt said.

In addition to the 36 passengers and the hijackers, the plane carried a crew of five, she said.