It will be years before the American economy fully recovers and repairs are completed to the global financial system, White House special adviser Paul Volcker said on Friday, warning also of risks to the stability of the euro.

At a gathering of top policy makers at the Spruce Meadows conference in Calgary, the head of President Barack Obama's economic recovery advisory board warned that the economic recovery does not yet fit any historic pattern.

"I think it is fair to say that we will not reach in the United States what's true in many European countries, true in Japan, we will not reach peak levels of production, past peak levels of production for several years even on a reasonably optimistic trajectory...assuming the economy grew by 3 percent a year," Volcker said.

"The American economy, beginning now, it will take three years or so to get back to previous peaks. That has not been a normal business cycle behavior, normal recovery."

He estimated it would take three to six years to repair the global financial system.

On European problems and the euro currency, he drew parallels with the United States.

"They show some of the same symptoms as we've had in the United States with the risk that it puts the stability of the euro itself in some jeopardy," he said.

"I'm a great supporter of the euro, but it's going to take a real effort there to stabilize the situation in Europe."