The Soyuz trio is due to dock on Thursday, joining the space station's present crew of three from the US, Russia and the Netherlands. Together, they will have the task of receiving the first ever cargo consignment for the ISS from a private freighter.

The unmanned Dragon spacecraft developed by the private firm SpaceX is due to be launched from Cape Canaveral, Florida, on Saturday and dock next week.

Russia is now the sole nation equipped to transport humans since the withdrawal from service of the last of the US space shuttles, the Atlantis, in July 2011.

Extra safety checks

Tuesday's Soyuz launch had been delayed by six weeks after an initial capsule was proved in testing not to be fully sealed. Safety was at the forefront after an unmanned Russian Progress cargo vehicle broke up in the atmosphere last August.

Russian mission control said Tuesday's launch went as planned. The rocket stages detached and all the crew were feeling good.

The trio in the Soyuz TMA-04M capsule heading for the ISS includes veteran Russian cosmonaut Gennady Padalka, who is on his fourth flight since 1998.
During his career he has spent 585 days in space and made eight spacewalks.

Also in the Soyuz is US astronaut Joseph Acaba and another Russian, Sergei Revin.

ipj/mz (AP, AFP)