Moscow has denied a report of trouble with a transport capsule docked to its orbiting Salyut space station, although it is hinting the two cosmonauts there may soon be brought back to Earth.
The alleged problem would be the third - and probably least serious - recent hitch for the Soviet space program, now concentrated on eventual assembly of a modular orbital complex around the Salyut spacecraft.
The report came from BBC radio in London, suggesting a fuel leak had in effect stranded the cosmonauts on Salyut and that a fresh Soyuz transport capsule would have to be sent to get them.
An official at the Soviet Academy of Sciences, contacted by a British reporter shortly afterward, denied there had been a fuel leak, and said: ''The flight is continuing normally. The state of the cosmonauts is good.''
Western experts here see no sign yet that a ''rescue'' mission, if it occurred, would necessarily be a perilous affair or imply any long-term slowing of Soviet space efforts.
In April, an earlier Soviet crew launched toward Salyut had to return to Earth without boarding the station when apparent guidance problems - which have intermittently nagged Soviet transport capsules - prevented docking.
Three weeks ago, in the most serious of recent problems, the rocket due to lift another crew toward Salyut exploded on launch. The cosmonauts' fail-safe mechanism allowed their capsule to parachute back to Earth, generally reliable Soviet sources say.
But they add that, despite initial indications to the contrary, the two men were at least slightly injured by pressure, estimated at 10 to 16 times normal gravity force during the mishap.
The sources deny reports from Washington suggesting that the crew had been meant to replace the two men aboard Salyut, saying a mere visit was planned.
Still, if the Salyut crew's original Soyuz transport craft, attached to one of two docking ports, is unusable, then the recent rocket explosion would leave the two cosmonauts stranded until a rescue is made.
The Soviets have indicated reluctance in the past to risk using their Soyuz transport capsules for a return voyage after more than about 115 days or so aloft - roughly the period the current crew has been on Salyut.
Western experts here suspect the scheduled Salyut visitors of late September may have planned to return in the older capsule and leave their newer one for the main crew's later flight home.
There have, meanwhile, been mixed public signals on when that return will come.
A Moscow Radio report early this month, when the crew had been aloft about three months, suggested their return was not imminent, detailing planned work on Salyut ''during their fourth month'' in space.
But some Western experts here discerned in a Moscow newspaper report Wednesday a hint that the two men aboard Salyut might be brought home early.
The report said the cosmonauts' physical condition, involving muscular contraction not before mentioned by the Moscow news media, had ''stabilized.'' The newspaper added that a recuperative program was ready for them back on Earth.
If there is indeed concern here over using the older Soyuz, a new capsule, possibly with only one man aboard, could be launched toward Salyut, then ferry all three cosmonauts home.
The older Soyuz would probably be uncoupled from Salyut without a crew, freeing a Salyut docking port for what Western analysts here believe will be the next major step in the Soviet space program: the third experimental launching and docking of a ''space module,'' of a sort designed eventually to convert Salyut into a larger, permanently manned orbital complex.
[If the Soviets asked for help, there's a ''definite chance'' that the American space shuttle Columbia would be able to rescue the Soviet cosmonauts, says one close observer of the US manned spaceflight program.
But on Monday, the Columbia had to return to its assembly building at Cape Canaveral, Fla., for work on one of its solid-fuel boosters. This has delayed the Columbia's Oct. 28 launch by at least a month. Still, if the Soviets sought help, the source says, the US could pull the European Spacelab out of the payload bay and add crew members who have been trained in rendezvous techniques, in time for a late November launch.
Assuming a successful rendezvous, there would still be the matter of transferring the Salyut 7's two-man crew to the shuttle. They would probably have to jump and drift across the gap bewteen the shuttle and the Soviet space station.]