There is no chance of US government bonds losing their gilt-edged rating, President Barack Obama's top economic aide said Sunday after China expressed unease over its enormous holdings of US debt.

Lawrence Summers, director of the White House's National Economic Council, said "no" when asked if Treasury bonds might lose their "AAA" rating from credit agencies because of the US economic crisis.

"They are the asset of choice for people around the world," he said on CBS program "Face the Nation," a day after Obama said China and every other foreign investor "can have absolute confidence" in their US government holdings.

"As long as we manage our economy soundly ... US financial markets will work themselves out, albeit with a period of difficulty," Summers said.

"There's one lesson from the history of financial crises that no one can argue with. They all end. This one will too," he said.

"What we just have to do is put in place the right policies step by step: jobs, housing, small business, credit, the banks."

Chinese Premier Wen Jiabao caused a stir Friday when he said his nation, the largest foreign holder of Treasury bonds, was concerned about its massive stake in the US economy.

"We have lent huge amounts of money to the United States. Of course we are concerned about the safety of our assets," Wen said.

Summers echoed Obama in arguing that despite the financial crisis, investment flows have actually increased into the United States.

"I think it is a recognition that the stability not only of our economic system but also our political system is extraordinary," Obama said Saturday after meeting Brazilian President Luiz Inacio Lula da Silva at the White House.

"Not just the Chinese government, but every investor can have absolute confidence in the soundness of investments in the United States," the US president said.