By Andrea Shalal and David Lawder

MARRAKECH, Morocco U.S. Treasury Secretary Janet Yellen on Friday told Reuters she had heard universal condemnation of Saturday's deadly attack on Israel by the military Hamas group at this week's annual meetings of the International Monetary Fund and World Bank.

The United States already had "lots of sanctions" on Hamas, and was constantly working to find a way to strengthen those, Yellen told Reuters in an interview.

(Reporting by Andrea Shalal and David Lawder)