MOSCOW, April 12 (Xinhua) -- The Russian and American space agencies signed a contract, under which the main crews and cargoes to the International Space Station (ISS) will be delivered by Russian spaceships, a senior Russian official said on Thursday.

    "Roskosmos and NASA signed a long-term contract till 2011, spelling out all obligations on the operation of manned spaceships of the Soyuz type and cargo spacecraft of the Progress type," Anatoly Perminov, head of Russian Federal Space Agency (Roskosmos), was quoted by the Itar-Tass news agency as saying.

    The contract "is more than 700 million" U.S. dollars, Perminov said.

    The signing of this document "clinched the legal formalization of Russian-American relations on the operation of the ISS concerning the delivery of crews and cargoes," he added.

    Under the contract, American astronauts will have only one place in the crews in the next missions to the ISS (Soyuz is designed for three people). "The correlation will change after 2009 when the ISS crew increases to six people," the Roskosmos head said.

    Duties of mission commanders would be performed both by Russian cosmonauts and American astronauts. "We shall decide for every separate flight, taking into account professional skills," Perminov added.

    According to NASA data, the contract sum is 719 million dollars. Six astronauts are to travel to the station by Soyuz spaceships in 2009, another six -- in 2010 and three -- in 2011. Besides, Progress ferries will deliver to the ISS and back to the earth 5.6 metric tonnes of various American cargoes.

    NASA also reserved for it a space -- 1.4 metric tonnes -- at a Russian cargo docking module whose dispatch to the ISS is planned in 2010. This is how NASA intends to meet its obligations on delivery of equipment to the station, designed for a Russian Multifunctional Laboratory Module.

    NASA promised to ship this equipment to the station by its shuttle, signing a new protocol with Roskosmos last summer on cooperation in the station's life support.

    NASA also agreed to pay Roskosmos for one more place aboard Soyuz for an astronaut from a partner country which built the station so that he would spend six months aboard and then return to the earth also by a Russian ship. A NASA press release does not indicate, from which country the astronaut will be. The flight is planned for 2009.

    NASA was forced to pay for places aboard Soyuzes and Russian ferries after the Columbia disaster in 2003 and subsequent suspension of flights by shuttles. President George W. Bush permitted to make payments to Russia in November 2005. Under the contract concluded with Roskosmos, NASA paid 43.8 million dollars in the first year of its operation.

    Last October, Americans extended the contract, promising to pay another 160 million dollars for the delivery to the station of its astronauts by two Soyuz spaceships in 2007 and 2008 and three tonnes of cargoes by eight Progress tugs over the same period.