Russia this week backed away from threats to shutter the international space station unless the United States or other countries pay it an additional $100 million this year to ferry astronauts and supplies to the orbiting structure while the U.S. space shuttle fleet is grounded.

The dispute over funding to speed up production of Russian spacecraft to service the space station has threatened to further strain U.S.-Russian relations. The dispute came at a time when Russia has condemned the U.S.-led war against Iraq and the United States has protested Russian transfer of nuclear, chemical and biological technology to Iran.

The announcement was welcome news for the beleaguered U.S. space program and comes three weeks before the Russians are scheduled to launch a Soyuz spacecraft from Kazakhstan carrying a two-person crew to relieve the two Americans and one Russian who have manned the space station since November. American Edward Lu, a physicist, and Russian Yuri Malenchenko, a pilot and engineer, will be aboard the Soyuz.

With the U.S. shuttle fleet grounded pending the outcome of an investigation into the Feb. 1 Columbia disaster, Russia's Soyuz space ships and Progress cargo craft are the only space vehicles available to transport people and supplies to the space station. Last month, senior Russian space agency officials threatened to mothball the space station -- which is expected to cost close to $100 billion when completed later this decade -- unless it received additional funds from the United States, Japan, Canada or the European partners in the venture.

But in a sudden turnabout, the Russian cabinet on Thursday pledged to speed up spending to build additional single-use Soyuz and Progress spacecraft until the three remaining shuttles have been cleared to fly again, which could take a year or two. Russian officials indicated that they were prompted by the fear that the space station might have to be left without a crew, which could put it at risk of falling out of orbit.

Russian officials said they would approve the early release of $38 million that had been budgeted for the latter half of the year to finance construction of two more Progress vehicles for this year and the next. They also tentatively pledged to nearly double their space agency's operating budget next year, from $130 million to $240 million -- but without indicating where the additional funds would come from.

"We will undoubtedly have to carry the main workload, having to perform additional launches and flights to the station," Prime Minister Mikhail Kasyanov said at the start of the cabinet session. "We can't postpone the decision. Space exploration has always been a priority" of Russians.

A shortage of water and other necessities created by the grounding of the three remaining space shuttles forced NASA to replace the three-member crew with rotating two-member crews.

That decision, announced Feb. 27 by NASA Administrator Sean O'Keefe, prompted concerns from lawmakers and independent experts who said they had been led to believe that a minimum of three crew members were needed to keep the station running properly and to perform scientific experiments. House Science Committee Chairman Sherwood L. Boehlert (R-N.Y). said, "Quite frankly, I think they were having difficulty doing meaningful science with the existing configuration" of three astronauts.

NASA officials said this week that the upcoming Expedition Seven mission is "on track" and expressed confidence that the new arrangement with the Russians will carry them through until the shuttles return to flight. The two-member crew will devote most of its energies to space station maintenance, officials say, but there will be time for scientific experimentation -- including the use of a recently reactivated microgravity glove box designed to develop and test scientific procedures for handling materials in space.

However, Mike Kostelnik, NASA's deputy associate administrator for the space station and shuttle programs, responded cautiously to the Russian cabinet announcement, saying that "I think we just have to wait and see what it means when it does play out.

"There's a lot of rhetoric as always around this particular issue [of funding] and a lot of things to be concerned with and, frankly, a lot of unknowns."

Officials of the countries participating in the space station program are working to iron out the details of Russia's enhanced role and responsibilities -- and to determine whether Russia will receive additional financial assistance. The latest talks were conducted via an international teleconference early Thursday.

NASA officials maintain they cannot pay for construction of any extra Russian space vehicles because of constraints imposed by the Iran Nonproliferation Act of 2000. Congress barred space station-related payments to the Russians unless the United States can certify that Russia has not transferred banned missile technology or technology for nuclear, biological or chemical weapons to Iran in the previous 12 months.

Some space experts and congressional aides said they were wary of the Russians' latest assurances, noting that the Russians have broken promises for meeting construction timetables and funneling U.S. funds to project contractors and subcontractors. A senior House Democratic aide who specializes in space-related issues said: "Until the money is in the hands of the contractors and the Progress production line has been suitably accelerated and augmented, you don't know really where you stand" with the Russians.

Sergei Chernikov, head of manned flight programs at Rosaviakosmos, the Russian space agency, said yesterday that his government's decision to reallocate funds this year "does not solve the issue of underfinancing, although we can now start buying parts and equipment."

He said the decision to speed up spending this year was essential because "we needed this money because our partners are not contributing anything and we had to start the process."

Staff writer Sharon LaFraniere contributed to this report from Moscow.

With the U.S. shuttle fleet grounded, Russia "will undoubtedly have to carry the main workload, having to perform additional launches and flights to the station," Prime Minister Mikhail Kasyanov said.