US President Barack Obama telephoned the leaders of Russia, France and Germany as he entered his first full week in office, White House spokesman Robert Gibbs said.

Obama spoke with German Chancellor Angela Merkel, Russian President Dmitry Medvedev and French President Nicolas Sarkozy, Gibbs said, promising further details later in the day.

In a statement, Sarkozy''s office said the French president and Obama discussed Afghanistan, the global economic crisis, and the new US leader''s promise to shut down the Guantanamo "war on terror" detainment camp.

Sarkozy and Obama agreed during their "warm," 30-minute conversation to work together in a "resolute fashion" on the economic emergency as world leaders prepare to meet in London in April, the statement said.

Sarkozy also restated France''s offer of cooperation on closing down Guantanamo and on Obama''s pledge to renew the NATO offensive in Afghanistan, and congratulated his commitment to Middle East peace, it said.

Merkel has been less forthright on Guantanamo and on Afghanistan, while Medvedev last week said Russia was ready to cooperate with Obama on Afghanistan and help with the transit of supplies and in the fight against terror.

But the Russian president, and Prime Minister Vladimir Putin, have also made clear that they expect Obama''s fledgling administration to work harder on US-Russia ties after prickly relations under president George W. Bush.