One US Marine was killed and four others wounded in action on Thursday while conducting a military operation south of Baghdad, the US military said in a statement.

"One US Marine was killed in action and four others wounded on Jan. 27 while conducting security and stability operations in Babil Province," the statement said, without elaborating.

The incident came one day after 31 US soldiers were killed in ahelicopter crash in western Iraq on the deadliest day for Americans since the Iraq war in March 2003.