LONDON, April 18 (Reuters) - European shares hit a three-week closing low on Monday, after Standard & Poor's cut its credit outlook on the United States to negative, with insurers exposed to U.S. equities among the biggest fallers.
The FTSEurofirst 300 index of top European shares fell 1.6 percent to end the session provisionally at 1,113.17 points, its lowest close since March 23.
Standard & Poor's on Monday downgraded its credit outlook for the United States, citing a risk that policymakers may not reach agreement on a plan to slash the huge federal budget deficit.
The STOXX Europe 600 Insurance Index fell 3.3 percent, with Allianz, Aviva, AXA and Generali down between 4 and 5.7 percent.
"S&P's statement doesn't say anything we didn't know before, but it crystallises people's worries. The U.S. deficit is too high -- we know that, but realistically things will probably change," said Andy Lynch, who managers 2.5 billion euros ($3.50 billion) for Schroders.
"I'm overweight insurers, so I'm having a bad afternoon." (Reporting by Brian Gorman)