Three astronauts returned to Earth Wednesday on board a Russian Soyuz capsule after a half-year mission on the International Space Station (ISS), landing in Kazakhstan, mission control in Moscow announced.

Russians Pavel Vinogradov and Alexander Misurkin landed on schedule at 8:58 am Kazakh time (0258 GMT) in the Kazakh steppe, along with American Chris Cassidy.

A live feed on Russian mission control's website showed rescuers extracting the three astronauts who were helped into chairs in the long grass of the steppe on a bright sunny morning.

"Everything went well, very smoothly," said Vinogradov, smiling as rescuers sponged his face.

"Pavel (Vinogradov) was leading us the whole way. It was just a memorable flight," said Cassidy, shaking hands with Vinogradov.

Vinogradov, 60, had been commander of the ISS with flight engineers Cassidy, 43, and Misurkin, 35. The group took off from Kazakhstan's Baikonur cosmodrome on March 29 and their mission lasted 167 days.

"The Soyuz TMA-08M capsule landed southeast of the town of Jezkazgan at 06:58 Moscow time. The landing went as planned," the Russian space agency said in a statement on its website.

Cassidy took part in a dramatic spacewalk in May with another NASA astronaut, Tom Marshburn. They managed to halt an ammonia leak to the station's power system that affected the US segment of the orbiting laboratory.

The three men were the first to take an express trip to the ISS in March, taking just under six hours instead of the usual two days to orbit and dock.

Under a new technique now employed by the Russian space agency, the Soyuz capsule only orbited Earth four times before docking at the ISS, instead of orbiting the Earth 30 times.

Misurkin was making his debut space flight, while Vinogradov was on his third space mission and Cassidy on his second.

Now left in the ISS are Russian commander Fyodor Yurchikhin and his flight engineers, Italian astronaut Luca Parmitano and Karen Nyberg of NASA.

In late September, they will be joined by American Michael Hopkins and Oleg Kotov and Sergei Ryazansky of Russia.