German Chancellor Angela Merkel refused to offer her backing, saying Greece must uphold its side of the bargain.
"It's obvious that the reforms that were agreed in the past are the right steps and that they therefore must be implemented."
Merkel, who invited the new prime minister of Greece, Antonis Samaras, to Berlin for talks, has consistently voiced her opposition to indebted countries winning easier terms without more stringent economic reforms.
European commission spokesman Amadeu Altafaj Tardio said any bond buying plan could only be a stopgap.
"If I could put this into everyday language, we're talking here about financial paracetamols," he said. "It may alleviate the tension, the pain … but it does not address the causes."
The Federal Reserve highlighted the euro crisis as a chief concern in its statement on the U.S. economy.
The committee said it "anticipates that the unemployment rate will decline only slowly toward levels that it judges to be consistent with its dual mandate. Furthermore, strains in global financial markets continue to pose significant downside risks to the economic outlook".
The Fed said it expected to keep interest rates exceptionally low at least until late in 2014.
Operation Twist involves the Fed selling medium-term bonds, and using the proceeds to buy longer-term bonds – such as 10-year Treasuries. In theory, such a move drives down the interest rate on 10-year bonds, taking down interest rates across the board. Mortgages are tied to 10-year Treasury rate and the move should bring down home loan rates.
Analysts said the Bank of England was poised to increase Q.E. next month after its nine strong Monetary Policy Committee (MPC) voted five to four against an increase this month, according to Bank minutes released on Wednesday, but highlighted the need for extra support in the coming months to prevent the U.K.'s recession worsening. King was one of three committee members to vote for an extra £50 billion and a fourth said he wanted a more modest £25 billion injection of funds against five members who voted to maintain QE at its current level.
The narrowness of the decision will heighten expectations of a further boost to Q.E. in July after another set of lacklustre economic figures, including a rise in jobless claims last month.
The governor was joined by Adam Posen and David Miles, who have consistently argued for Threadneedle Street to support cash-strapped banks and combat deflationary pressures in the economy with a higher level of bond purchases.
A group of hawks led by deputy governors Paul Tucker and Charles Bean said that while the economy needed extra monetary support, a further round of bond purchases could be swallowed by banks desperate to build up their reserves.
The minutes show the hawks expect the Financial Policy Committee, which oversees banking regulation, to support looser rules covering bank reserves to ease credit. The parlous state of the U.K.'s bank finances remains much of the focus of the MPC, according to the minutes.
They said: "It was possible that the impaired U.K. banking system, coupled with a heightened perception of risk stemming from the euro area, had been a larger impediment to the recovery of both demand and potential supply capacity than previously thought likely: the weakness of lending, housing market transactions, business investment and productivity growth were all possible symptoms of that."
The committee agreed the downside risks to the economy appeared to have grown.
"The near-term outlook for U.K. activity had softened, and output appeared to be slowing in the euro area, United States and some emerging economies. Set against that, short and longer-term market interest rates had fallen on the month and this would provide some stimulus. More significantly, however, the risks to U.K. and global activity from financial distress and political tension within the euro area had intensified again. The likelihood of a disorderly outcome looked to have increased, and that could, if it crystallized, have a significant effect on global demand and the stability of the banking system, including in the United Kingdom."
Intellpuke: You can read this article by Guardian Economics Correspondent Phillip Inman in context here: www.guardian.co.uk/business/2012/jun/20/federal-reserve-pumps-more-money-us-economy