Engineers monitoring the docking via a video feed from the Soyuz TMA-6 spaceship broke into applause when they saw that the automatic docking system had worked flawlessly.

A little more than two hours after the 0220 GMT link-up, Russian Sergei Krikalev, American John Phillips and Italian Roberto Vittori, who blasted off on Friday from the Baikonur cosmodrome in Kazakhstan, met face-to-face with the two men who have spent the past six months aboard the orbiting station.

The newcomers were greeted by Russian cosmonaut Salizhan Sharipov with the traditional Russian welcome offering of bread and salt and his crew mate, US astronaut Leroy Chiao, who are both scheduled to return to Earth on 25 April, along with Vittori, who is representing the European Space Agency.

Later on Sunday, the five men began unloading 150kg of scientific equipment, documentation, personal belongings and fresh vegetables carried up on the Soyuz capsule.

Experiments

Aboard the rocket were worms
and pregnant crickets

Among the supplies were worms and pregnant crickets for some of the myriad scientific experiments conducted aboard the station.

About 70% of the experiments will be devoted to medical research, said Mission Control chief Vladimir Solovyov.

Givi Gorgiladze, of the Russian Academy of Sciences, told the Itar-Tass news agency the worms will be used to study regeneration in a weightless environment, while pregnant crickets will be monitored for nerve-cell formation.

The projected mission

One of Krikalev and Phillips' key tasks during their six-month mission will be to observe the condition of the US space shuttle Discovery when it arrives in the first shuttle launch since the Columbia shuttle disaster on 1 February 2003.

The two will conduct a photo survey of the Discovery's insulating tiles as the shuttle manoeuvres to dock.

Fred Gregory, deputy administrator of the US space agency Nasa, said that the resumption of US space shuttle flights was on schedule.

"The return to flight activities for the shuttle appears to be on time and we are very hopeful we will be able to launch within the first window, in middle May or early June," Gregory said.