File picture shows Russian cosmonaut Alexander Skvortsov (R) and US astronaut Tracy Caldwell Dyson chatting prior to launch in April. The Soyuz spacecraft carrying Dyson, Skvortsov and Russian cosmonaut Mikhail Kornienko landed safely from the International Space Station Saturday, mission control said, after delays in undocking kept the astronauts an extra day in orbit.

A Russian Soyuz capsule with three crew landed safely back on Earth from the International Space Station on Saturday after unprecedented problems undocking kept astronauts an extra day in orbit.

"The landing was without incident. The crew feels normal," a spokesman for the Russian mission control outside Moscow said.

Russia's space agency Roskosmos said the craft carrying US astronaut Tracy Caldwell Dyson and Russian cosmonauts Alexander Skvortsov and Mikhail Kornienko had landed on time at 9:23 am (0523 GMT) in the Kazakh steppes.

The first television images beamed from the space station showed the three-member crew who had remained behind pumping their fists and cheering the safe landing.

Mission commander Skvortsov was the first to be helped out of the capsule and wrapped in a blue thermal blanket after the arduous flight.

Grinning widely, flashed an okay sign to cameras and bit into an apple, the first food traditionally given to the crew after landing.

"It was all superb up until the very last minute, the landing. I feel great," Skvortsov beamed. "You saw for yourself, we met the Earth softly and tenderly."

But Kornienko joked he had no desire to chomp on an apple. "We have to change tradition, I want a cucumber! I haven't had a cucumber in half a year," he told the cameras.

NASA astronaut Dyson, the only crew member to have previously flown into space aboard the US shuttle Endeavour, was shown speaking to loved ones by satellite phone at the landing site, about 35 kilometres (20 miles) from the remote central Kazakh town of Arkalyk.

The crew had been scheduled to make their drop to Earth on Friday but the descent was delayed by 24 hours after the Soyuz craft failed to undock for the first time in a decade of ISS flights.

Crew members were forced to add an extra day to over six months in orbit over fears that the capsule was not fully airlocked after a computer malfunctioned.

"We confirmed that the signal on a loss of air pressure was false, carried out troubleshooting and discovered the problem was purely mechanical," Roskosmos chief Anatoly Perminov was quoted by Russian news agencies as saying.

"One bolt was broken," he explained of Friday's failure to undock. "The most important thing is that the technical group resolved all the problems in a short time."

The head of Russia's Energia space corporation, the Soyuz's designer which was brought in to troubleshoot, confirmed a tiny bolt had prevented flight controllers from undocking the Soyuz.

"A small screw or bolt got stuck in the gear mechanism," Vitaly Lopota said in televised comments. "As a result the contact group did not function, which blocked the electromechanic hooks anchoring the spacecraft to the station."

Perminov had said Friday that on the crew's first undocking attempt, one of their computers sent up a red flag showing the airlock was not fully sealed.

"I thank everyone," he said. "The crew members have proved themselves to be competent experts. They were able to make this happen in a very short time."

While Friday's docking problem was the first involving the Soyuz, it was the third at the station in four months after the automatic system failed on two unmanned Russian Progress supply shuttles, causing one to fly past the station in June.

The string of mishaps in a space programme that usually strives for and achieves pinpoint accuracy comes just before NASA mothballs its shuttle later this year, leaving the ISS entirely dependent on the Russian Soyuz.

(c) 2010 AFP