Russian cosmonaut Fyodor Yurchikhin, and two American astronauts, Shannon Walker and Douglas Wheelock, touched down safely on Thursday near the town of Arkalyk on the steppes of Kazakhstan, the former Soviet Republic that still hosts most of Russia's space programme.

The astronauts were originally scheduled to return on 30 November, but officials in Kazakhstan instructed Roscosmos, the Russian Space Agency, to keep Kazakh airspace clear for December 1 and 2, when the country is hosting a summit of the Organisation for Security and Cooperation in Europe (OSCE). .

Arkalyk is more than 400 miles from Astana, the Kazakh capital, where the summit will be held.

The early return is the most extreme in a long list of measures taken by Kazakhstan to ensure the success of the prestigious summit, which will be attended by Hillary Clinton, the US Secretary of State, and Nick Clegg, the British Deputy Prime Minister.

The summit, the OSCE’s first in 11 years, is a diplomatic coup for Kazakhstan, which this year became the first former Soviet Republic to chair the organisation.