The White House on Monday urged the Greek government to move as quickly as possible to fulfill its commitments under a debt rescue package, as speculators pounded on weakened euro zone bond markets.

We welcome the consensus that has been reached in Greece over the need to implement the country's reforms, commitments to the IMF (International Monetary Fund) and the European Union, and we urge the government to move as quickly as possible to fulfill the commitments, said White House press secretary Jay Carney.

U.S. President Barack Obama took part in a G20 summit in Cannes last week dominated by the euro zone debt crisis but European leaders were unable to find new money to beef up a rescue plan that quickly came under attack from speculators.

European markets gyrated on Monday as Italian Prime Minister Silvio Berlusconi defied pressure to resign and the Greek government scrambled to form a new government of national unity after Prime Minister George Papandreou stepped down.

We continue to call on Europe, and work with our European counterparts, to implement those decisions rapidly and to reach a conclusive end point in terms of dealing with this problem, Carney told a White House news briefing.