MOSCOW - A Russian space capsule touched down in Kazakhstan hundreds of kilometres off target on Saturday after hurtling through Earth's atmosphere in a steeper-than-normal descent.

Officials say the three astronauts on board were unharmed. But it was the second time in a row -- and the third since 2003 -- that a Soyuz landing has gone awry.

Saturday's mission saw the return to Earth of South Korea's first astronaut, Yi So-yeon.

She spent 10 days in space before joining U.S. astronaut Peggy Whitson and Russian flight engineer Yuri Malenchenko in the 3 1/2-hour, bone-jarring descent from the International Space Station.

Russian engineers target returning capsules to a landing site near the town of Arkalyk in Kazakhstan's barren north. But after entering the atmosphere, the TMA-11 capsule for some reason began a "ballistic trajectory.''

Mission Control spokesman Valery Lyndin says that subjects the crew to G-forces more than double what occur under normal circumstances.

Parachutes eventually slowed the craft and dropped it onto the Central Asian steppes in a puff of dust about 20 minutes late and some 420 kilometres  off target.

It took another 25 minutes before search helicopters could locate the capsule and determine the crew was unharmed.

Medical officials said they were in satisfactory condition, but gave no details.

"The most important thing is that the crew is healthy and well,'' Federal Space Agency chief Anatoly Perminov told a post-landing news conference. "The landing occurred normally, but according to a back-up plan -- the descent was a ballistic trajectory.''

Perminov said engineers would examine the capsule to determine what caused the glitch, though he blamed the Soyuz crew for not informing Mission Control about the unusual descent.

Later, Perminov was asked about the presence of two women on the Soyuz, and referred to a naval superstition that having women aboard a ship was bad luck.

"You know in Russia, there are certain bad omens about this sort of thing, but thank God that everything worked out successfully,'' he said. "Of course in the future, we will work somehow to ensure that the number of women will not surpass'' the number of men.

Challenged by a reporter, Perminov responded: "This isn't discrimination. I'm just saying that when a majority (of the crew) is female, sometimes certain kinds of unsanctioned behaviour or something else occurs, that's what I'm talking about.''

He did not elaborate.

Yi, a bioengineer who was initially an understudy for the mission, travelled to the station on April 10, along with cosmonauts Sergei Volkov and Oleg Kononenko. South Korea paid Russia $20 million for the flight.

In South Korea, several hundred people gathered at the Seoul's Olympic Park to watch together Yi's return on a giant television screen, clapping and cheering after a broadcaster reported the landing.

"I'm happy and feel grateful as she safely returned,'' Yi's mother, Jung Geum-sun, told the SBS television network. "I want to hug her, tell her: 'you worked hard.'''

Whitson and Malenchenko spent roughly six months performing experiments and maintaining the orbiting station and were replaced by Volkov and Kononenko. They joined American astronaut Garrett Reisman, who arrived last month on the U.S. space shuttle Endeavour.

According to the U.S. space agency NASA, Whitson, 48, set a new American record for cumulative time in space -- 377 days.

It was the second landing in a row of a Soyuz capsule that has gone awry. In October, a glitch sent Malaysia's first space traveller and two Russian cosmonauts on a steeper-than-normal path during their return to Earth.

A similar problem occurred in May 2003 when the three-man, Russia and U.S. crew also experienced a steep, off-course landing. It then took salvage crews several hours to locate the spacecraft because of communications problems.

Despite the mishaps, the Russian space program has a reputation for reliability.

The single-use Soyuz and Progress vehicles have long been the workhorses of the space station program, regularly shuttling people and cargo to the orbiting outpost. They took on greater importance following the grounding of the U.S. space shuttle fleet in the wake of the 2003 Columbia disaster.