Russian President Vladimir Putin will meet his U.S. counterpart Barack Obama on the sidelines of the upcoming G8 summit in June, a Kremlin aide said Thursday.

"I would like to stress that the presidents have agreed for certain to hold a full-scale meeting associated with the G8 summit in Northern Ireland," Yury Ushakov told reporters.

He did not rule out the possibility that the presidents would meet during a G20 summit in St. Petersburg due in September.

The official said Putin had reaffirmed an official invitation to Obama during a recent telephone conversation.

"I think (U.S. National Security Advisor Thomas) Donilon will come to Moscow and send some signals on this account as well," the Interfax news agency quoted him as saying.

Both sides agreed to make "essential preparations" so that the meeting in Northern Ireland would be "substantive," Ushakov said.

He said the possible meeting between Putin and Donilon when the latter visits Russia on April 15 would depend on Putin's schedule. Endi