US President Barack Obama knew about the FBI operation to smash an alleged Russian spy ring before meeting President Dmitry Medvedev last week, but did not raise it at the talks, an aide said.

But the White House said the revelations, which were condemned by Russia, would not interfere with the effort by both sides to "reset" their relations, which has been pursued ever since Obama took office last year.

The alleged operation was busted just a few days after a warm summit between Obama and Medvedev at the White House at which both sides made an elaborate effort to bury any lingering Cold War tensions.

"I do not believe this will affect the reset of our relationship with Russia," White House spokesman Robert Gibbs said.

"We have made great progress in the past year and a half. I do not think this will affect those relations."

Gibbs said Obama had been briefed on what he termed a law enforcement issue and had known about it before he met Medvedev, but did not raise it at the talks and a joint trip to a burger joint in suburban Virginia last week.

The State Department meanwhile said the 11 alleged Russian agents arrested this week were "vestiges" of "old attempts to use intelligence," but the relationship between the two Cold War foes was still improving.

"We're moving towards a more trusting relationship. We're beyond the Cold War; our relations absolutely demonstrate that," said Phil Gordon, the assistant secretary of state for European Affairs.