Russia could become a full partner in a planned U.S.-European Mars exploration mission, a European Space Agency spokesman said.

Senior NASA, ESA and Russian space agency Roscosmos officials have agreed to continue talks on the issue, ESA's Franco Bonacina said.

ESA Science Director Alvaro Gimenez Canete met with Charles J. Gay, NASA Associate Administrator, and deputy Roscosmos head Anatoly Shilov at ESA headquarters in Paris Wednesday, RIA Novosti reported.

The meeting "ended with optimism" that Russia could provide a Proton rocket to launch a European-led Mars mission in 2016 in exchange for full membership in the exploration project, Bonacina said.

ESA's ExoMars project is facing difficulties due to a reduction of financing from NASA.

Oleg Korablyov, a deputy director of Russia's space research institute, said Russian scientists are interested in joining the project to speed up the development of his country's own program of Mars research as well as cut its expenditures.

All of Russia's 17 independent attempts to study Mars since 1960 have failed, NASA said.