Two Russian cosmonauts and a German astronaut will have to spend an extra 44 days aboard the space station Mir because a lack of funds has delayed construction of the rocket that will bring their replacement crew, Russian and European space officials said Thursday.


Though a formal announcement of the delay was not to be made until Friday, executives at the Russian Space Agency and their partner on the joint mission, the European Space Agency, said they were now negotiating modifications to what was supposed to be a 135-day flight.


While all sides said there was no cause for alarm and that the cosmonauts are not stranded, extending a mission due to a lack of funds will come as a blow to the image of the struggling Russian space program.


"It is a major black eye," said Daniel Van Hulle of the Moscow office of ANSER, an aerospace consulting agency. "Something like this is the greatest fear that everybody has."


Asked if he was worried that the image of Russia's space program would be damaged by a delay due to lack of funds, Boris Razumov, spokesman for the Russian Space Agency, or RKA, said, "We are worried. But that's our internal worry. It's not a tragedy. Everyone's budget is limited."


The holdup in construction of the Soyuz U-2 launcher at the Progress plant in Samara does not come as a complete surprise, however, said ESA spokesman Franco Bonacina, adding that both sides knew from the start that the mission might have to be extended.


"It was one of the options that was devised in the general programming of the launch," Bonacina said from ESA headquarters in Paris.


Officials at RKA said Thursday that they had been exploring two alternatives for the future of the Mir mission for some time, and were waiting for this week's successful docking of a supply ship before making their decision.


The three men were supposed to return from space Jan. 16, but now that the supply ship has docked it has become possible to extend the mission.


"The question has been whether to apply all our forces to build this rocket on time, or to see if we might not have to, and whether that suits the European Space Agency," Razumov said. "They are reacting positively."


But however the delay is packaged, it cannot be welcome to Russia's space program, once the pride of the former Soviet Union.


Russia is a major player in the construction of the international space station Alpha and also hopes to operate commercial satellite launches from the Baikonur cosmodrome in Kazakhstan. Financial delays like this must make international space partners -- and potential launch customers -- nervous.


"This is NASA's worst nightmare, as far as the space station is concerned -- something not being on schedule because of the fact that the Russian system is falling apart," Van Hulle said. "For commercial launches, that is their worst nightmare, too."


Razumov said financial difficulties should not affect commercial launches, which are executed by contract and require payment in advance, he said.


And NASA, he said, has nothing to fear because the space station simply will not get built without the Russians. Moreover, NASA has its own problems, Razumov said, citing the repeated delays in launches of its space shuttles.


Years ago, the Soviet space program would build rocket after rocket and store them until they were needed, Van Hulle said. The stockpile, though, must have run out.


"After the Soviet Union fell apart, they were able to maintain their launch rates because they had a lot of launch vehicles produced. It has been a mystery how many of these vehicles they had because it was classified," Van Hulle said.


"Everyone knew the stockpiles were dwindling, but it looks like they've reached the point where they have to build a new rocket for every launch," he said.


The Progress plant, he said, is not getting paid by the Russian Space Agency, which administers civilian space exploration. The RKA, in turn, is not getting its money from the federal budget, which allocated 50 percent less for space exploration than it did in 1994. And even that money is not being released from the treasury promptly.


"This is happening all the time, as far as companies and subcontractors not getting paid on time. We hear it almost every day," Van Hulle said.


In the meantime, ESA is trying to make the most of the situation. Alain Fournier-Sicre, the agency's Moscow representative, said German astronaut Thomas Reiter will now have the chance to conduct additional experiments.


"After this trip is completed, we will have had the longest trip in orbit for a Western astronaut," he said. "The extension might allow us to pursue some additional experiments, and it might be very interesting for us."


Mir's oxygen and water supplies are constantly recycled, so it is virtually impossible to run out of air and water on board. And with the delivery of additional supplies earlier this week, the three men aboard will have more than enough food to make it through the extra 44 days, Razumov said.


The capsule that brought Reiter and his partners, cosmonauts Yury Gidzenko and Sergei Avedeyev, up to Mir from the Baikonur Cosmodrome Sept. 3 is now docked with the space station. It could bring them down at any time in the event of unexpected difficulties.