MOSCOW (AFP) - South Korea's first astronaut ended her nine-day stay on the International Space Station on Saturday as her spacecraft began a three-and-a-half hour descent to Earth, a Russian official said.

Her Soyuz TMA-11 undocked from the ISS at 0506 GMT to begin its 350-kilometer (220-mile) return trip to ex-Soviet Kazakhstan, said Nikolai Kluchkov, a spokesman for Russian mission control.

"The craft will land at 12:31 Moscow time (0831 GMT) around 80 kilometres north of Arkalyk in Kazakhstan," he said.

As well as Korean scientist Yi So-Yeon, the Russian-built Soyuz was carrying US astronaut Peggy Whitson and Russian flight engineer Yury Malenchenko.

The three crewmembers were shown on Russian television embracing their three colleagues in the weightlessness of the ISS before climbing into the cramped Soyuz landing pod, waving as the hatch closed behind them.

A camera on board the Soyuz showed grainy images of the ISS slowly shrinking into the distance as the craft began its descent.

Yi, a biosystems engineer, carried out 18 experiments, including biological, geophysical and medical tests, Russia's RIA-Novosti news agency reported.

South Korean President Lee Myung-Bak earlier hailed Yi's mission as the start of a "march towards space" for his country, which is due to launch a satellite from its own space base later this year.

Whitson spent 191 days in space, bringing her career total to 377 days, more than any other American. She was replaced as commander by Russian Sergei Volkov, who at 35 is the youngest person ever to run the ISS.

Volkov is the son of former Russian cosmonaut Alexander Volkov, who launched from the Soviet Union and returned only after the Soviet collapse of December 1991, the two forming the first father-and-son space dynasty.

The ISS, which circles the Earth at a speed of 28,000 kilometres (17,000 miles) per hour, has accommodated 156 astronauts from 15 countries, as well as five "space tourists."

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