The International Monetary Fund cut its forecast for U.S. growth in 2011 for the second time in two months, warning that further setbacks to a recovery pose growing threats to the world economy, along with potential contagion from the European debt crisis.

The U.S. economy will grow 2.5 percent this year and 2.7 percent in 2012, down from the 2.8 percent and 2.9 percent projected in April, the IMF said today, citing higher commodity prices and bad weather in the first quarter and a weak housing market. The Washington-based IMF now sees the world economy expanding 4.3 percent this year, down from 4.4 percent two months ago. It left a 4.5 percent forecast for next year unchanged.

"Global activity is projected to slow in the second quarter of 2011, and then reaccelerate in the second half of the year," the IMF said in an update of its World Economic Outlook report. "Greater-than-anticipated weakness in U.S. activity and renewed financial volatility from concerns about the depth of fiscal challenges in the euro area periphery pose greater downside risks."