MOSCOW (Reuters) - Russia dismissed on Friday U.S. concerns that failing equipment was endangering crew safety on the International Space Station, saying NASA was simply in the dark about the situation on board since grounding its shuttles.

The Washington Post reported Thursday that several officials from the U.S. space agency had refused to sign off on the current 200-day mission by American astronaut Michael Foale and Russian Alexander Kaleri because air and water monitors on the ISS were in disrepair. "Nothing has changed on the station," Sergei Gorbunov, spokesman for Russia's space authority Rosaviakosmos, told NTV television. "The crew are all right. They have everything, including air of proper quality."

"All air-monitoring and air-supplying equipment is functioning properly. There are no problems. The only problem is that the shuttles are not flying. And that has disrupted data processing from the U.S. segment of the station," he said.

Foale, the newest ISS commander, told an orbit-to-Earth news conference on Thursday he and his Russian colleague were aware of safety objections within NASA to their flight, launched last week. But both felt perfectly safe. Ed Lu, the U.S. astronaut Foale is replacing, dismissed the report of health concerns as "overblown."

Gorbunov said the United States raised the safety issue after Russia turned down its request to bring down a malfunctioning gas analyzer, a replacement for which was sent to the ISS in August.

Gorbunov told Itar-Tass news agency Moscow refused because there was no room in the capsule taking the crew back to Earth.

The $95-billion space platform depends on spacecraft from cash-strapped Russia to ferry crews and equipment to and from Earth. NASA grounded all shuttles after the Columbia disintegrated on reentry in February killing all aboard.

Russian astronaut Yuri Malenchenko, the outgoing space station skipper, mentioned the Columbia accident during a brief change-of-command ceremony on Friday aboard the ISS.

"We have continued the work because, among other things, our friends have given their lives," Malenchenko said.

He noted his crew had to be reduced from three men to two after the shuttles were grounded, and that resources on the station have been limited.

To maintain adequate water supplies, Malenchenko and Lu had to recycle the sweat from their dirty laundry while in orbit. Foale told them: "You have handed us a space station that is in excellent condition. We will do everything we can to pass on the International Space Station to the next visitors, the next crew, in as good a condition as you have given it to us."

Foale and Kaleri, who flew to the platform along with Spaniard Pedro Duque, are to remain aboard the ISS for six months. Duque, on a 10-day mission, returns to Earth next week with the crew being replaced.

Foale and Kaleri are scheduled to perform a spacewalk during their stay. With crew size limited by the absence of shuttles, this will be the first such operation conducted without backup from a third person inside the station.

NASA experts have said their concern was over equipment monitoring the air and water for complex hydrocarbons and toxic microbes. Foale said those could only be introduced through something as catastrophic as fire or contaminated supplies.

The safety issue was raised in May when rescuers spent hours looking for the previous mission's crew after they landed hundreds of miles off target in the steppes of Kazakhstan.