Russia has "decided to concentrate the necessary resources to construct an additional spacecraft" for supplying the station with food and water, Putin told the cosmonauts aboard the ISS, via a link from the Saint Petersburg military and space academy.

"If necessary, the question of further financial participation will be examined," he said.

After the US Columbia space shuttle disintegrated on February 1, killing all seven crew, NASA halted all planned flights to the ISS. Russia's spacecraft are now the only means of transporting crew and supplying the ISS.

Two US astronauts and one Russian cosmonaut arrived on the ISS for a four-month mission in early December.

"Today, while shuttle flights have been temporarily suspended, it is important to maintain the operating capacity of the ISS... I understand Russia's responsibility in this situation," Putin said.

The president acknowledged that the cosmonauts' mission had lasted longer than planned and congratulated them for their work.

"You were forced to keep on working without a break in the dramatic weeks following the Columbia catastrophe. And you did so without fail," Putin said.

Saturday marked the 42nd anniversary of the first flight into space by Russian space hero Yuri Gagarin.

Moscow admitted for the first time this month that it would have to fund extra flights to the ISS following the United States' decision to ground its shuttle program.

The Russian government decided to earmark an additional 1.2 billion rubles (38 million dollars, 35 million euros) in budgetary funds to the space programme over the next six months.

SPACE.WIRE