The first flight of the Soviet Union's space shuttle, which officials previously have said would be unmanned, probably will carry two crew members, the official Tass news agency said Saturday.

"The Soviet reusable spaceship will probably be carrying two persons on its maiden flight, just as the U.S. space shuttle did on its test mission," Tass quoted Vladimir Shata-lov, chief of cosmonaut training, as saying.On March 18, Alexander Dunayev, head of the Soviet space agency Glavkosmos, told a news conference that scientists were working around the clock to prepare for the first launch of the space shuttle before June.

He said at the time that the initial flight would be unmanned and implied that the Soviet Union was more concerned about the safety of its space crews than the United States.

"We pursue the fundamental objective: whether man is alive or dead after the flight. On the basis of that we regard the fundamental differences between the Soviet direction of development and the U.S. part of development," he said.

The U.S. space shuttle program was grounded after the explosion of the space shuttle Challenger in January 1986 that killed all seven crew members.

Western experts say the Soviets also have lost crews on space missions and in training. The Soviet space effort traditionally has been shrouded in secrecy, and little information has been released.

Tass quoted Shatalov as saying the shape of the Soviet space shuttle is similar to that of the U.S. craft since both must perform like a supersonic airplane when returning to Earth.

But Shatalov was quoted as saying that while the United States has a booster rocket specifically designed to launch its shuttle, the Soviets are launching theirs with the more powerful Energia booster, which also can be used to send other payloads into space.

Tass did not say when the shuttle would be launched.