The two countries "have agreed to begin joint exploration of Mars and carry out joint unmanned interplanetary station flight programmes," Sergei Gorbunov, spokesman for Russia's Rosaviakosmos space agency, told the Interfax news agency.

"In addition, it was decided that Russia can take part in US space tenders," Gorbunov added.

NASA administrator Sean O'Keefe held talks with his Russian counterpart Yury Koptev to discuss cooperation including over the 16-nation International Space Station (ISS).

In May 2001 the Russian Space Agency announced a tender for designs for a manned flight to Mars, with experts saying they expected the final plans to be announced in 2005.

Last year Russian space experts urged their US and European colleagues to join them in launching a manned flight to Mars by 2014.

Many experts believe January 2014 would be a propitious date for a Mars exploration bid because an exceptional alignment of Earth, Mars and Venus that year would provide an escape route back to Earth in the event of a breakdown by means of a gravitational slingshot effect.

The US space agency NASA is currently engaged in small-scale studies on manned flight to Mars but has no plans for a mission.

Information obtained from unmanned flights to Mars has revealed that the planet has a very thin atmosphere and, although there is no liquid water, scientists believe it is possible the climate could sustain life in the form of micro-organisms.

SPACE.WIRE