US President Barack Obama overnight complained that Europe's financial crisis was scaring the world and was rooted in the eurozone's failure to fix its banks.

In a new sign of US frustration about a situation that many in Washington fear could further derail the US recovery, Obama mentioned the eurozone turmoil as one foreign factor which had helped to slow America's economy.

"In Europe ... you know, they have not fully healed from the crisis back in 2007 and never fully dealt with all the challenges that their banking system faced," Obama said at a forum hosted by the LinkedIn social network.

"It's now being compounded with what's happening in Greece. So, they're going through a financial crisis that is scaring the world.

"And they're trying to take responsible actions, but those actions haven't been quite as quick as they need to be."

After weeks of saying Europe had the capacity to meet its sovereign debt crisis, US officials have been showing signs of increasing impatience with EU political leaders as fears spread of contagion from the eurozone crisis.

US Treasury Secretary Timothy Geithner last week said America had a huge stake in helping Europe find a "more effective strategy" to tackle its financial crisis.

European and US shares rose on Monday with intense speculation over a more ambitious bailout fund for the eurozone and an orderly Greek default, though lack of details and denials by officials kept trading volatile.

But Germany shot down moves to boost European debt rescue funding, and Greece languished without a date for the return of auditors blocking loans it needs to avoid default.