"A woman's organism is different, that's why we need to modify some of the life systems in the capsule," Nikolai Sevastyanov, head of the RKK Energia space corporation was quoted by ITAR-TASS as saying.

Anousheh Ansari of the United States is set to blast off from Russia's Baikonur cosmodrome in Kazakhstan on September 14, taking the place of Japan's Daisuke Enomoto, who failed medical tests this month.

A Russian space expert, who preferred to remain anonymous, told AFP the main change on the capsule for Ansari would be to provide "special equipment for the toilet."

Engineers will also replace a seat in the Soyuz that had been tailor-made for Enomoto with another that fits Ansari and come up with a programme of scientific tests for Ansari to carry out, Sevastyanov said.

Ansari's trip is set to be formally approved at a meeting next week.

"We have taken a preliminary decision on the participation of Anousheh Ansari for the September mission," Igor Panarin, a spokesman for Russian space agency Roskosmos, told AFP.

Ansari, a US national of Iranian origin, and fellow crew members Mikhail Tyurin from Russia and Michael Lopez-Alegria of the United States, are taking final tests this week at the Star City training centre near Moscow.

Soviet cosmonaut Valentina Tereshkova was the first woman to fly into space aboard the Vostok-6 capsule in 1963.

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