ROME - Support for Italian Prime Minister Silvio Berlusconi and his government have hit record lows, an opinion poll showed on Monday, and the centre-left has overtaken the centre-right in terms of voting intentions.

The survey by the IPR polling institute for the left-leaning La Repubblica daily showed Berlusconi's approval rating at 31 percent in April, down from 40 percent at the start of 2011 and 56 percent in April 2009.

The survey reflects a steady decline in Berlusconi's popularity, dented by corruption and underage prostitution trials that have opened against him.

Some 58 percent of respondents said they had little or no confidence in Berlusconi, up from 55 percent in the first three months of 2011.

Confidence in his centre-right government fell to 23 percent from 26 percent a month ago and less than half the level of 55 percent registered in June 2008, shortly after taking office. The approval ratings of several ministers also declined.

Berlusconi has started campaigning for elections due on May 15 to elect the mayors of cities such as Milan, Turin and Naples.

The vote is seen as a test for the government, which has faced criticism for its approach to fighting in Libya, its handling of a surge of immigrants fleeing North Africa and its proposed reforms to the justice system.

When asked on voting intentions, 41.5 percent said they would vote for parties on the centre-left, up marginally from 41.2 percent a month ago and topping the 41.0 percent who said they would vote for parties on the centre-right.

More than 40 percent of respondents said they remained undecided about how to vote.