Russian president Vladimir Putin says he will not be attending the G8 summit in the United States later this month.
Mr Putin, who was sworn in for a third term earlier this week, says he will send Prime Minister Dmitry Medvedev in his place.
Mr Putin told US officials he was busy finalising his cabinet.
The two presidents will now hold talks at the G20 meeting in Mexico in June.
In a statement, the White House said President Putin "expressed his regret" to President Obama by phone.
The US is hosting the G8 summit of seven of the world's most industrialised nations, and Russia, at Camp David on 18-19 May.