A Soviet offer to provide launching capabilities for American commercial satellites has been blocked by the United States, the State Department said yesterday.

Soviet officials who discussed the initiative with U.S. officials "have been clearly informed of the longstanding prohibitions on the transfer of U.S. space technology to the Soviet Union," the department said in a written statement.

"They have also been informed that no change is contemplated in this policy, nor are we seeking a waiver to existing laws, regulations or policies," the department added.

After the space shuttle Challenger exploded and several other rocket malfunctions left the United States without the ability to launch large satellites into orbit, the Soviet Union last year offered commercial space launch services to American business.

Since then, the Soviets "have attempted to establish the infrastructure and merchandising techniques to market the use of Soviet boosters, particularly the Proton launch vehicle," the department said.

{The Washington Post reported last week that, according to officials of U.S. aerospace firms that were negotiating with the Soviets, bargain prices were offered. One official quoted a price of $30 million to put a 4,000-pound spacecraft into orbit 22,500 miles above the Earth, half of what U.S. launching companies or Europe's Arianespace would charge.

{It has been estimated that between 60 and 75 commercial satellites with a market value of $7 billion are awaiting launch because of the inability of the United States to put satellites into space, The Post reported.}

But U.S. arms control laws -- specifically, the International Traffic in Arms Regulations (ITAR) -- prohibit transfer to the Soviet Union of U.S.-origin technology that is used in the communications satellites of the United States and other western nations, the State Department said yesterday.

"Launch vehicles, other spacecraft, space electronics and related technologies and technical data and information required to integrate this equipment is similarly controlled and would not be permitted to be exported to the U.S.S.R.," the State Department said.

{United Press International reported that Ford Aerospace & Communications Corp. and Hughes Aircraft Co. had been in contact with the Soviet Union.}