Silvio Berlusconi, Italy's prime minister, was dealt a blow on Monday when an opinion poll showed a collapse in support for his Forza Italia party and his leadership of the Italian centre-right.

With a national election due by May, a survey by the SWG research institute put Forza Italia's support at 17.5 per cent, the party's lowest score since it swept to power in 2001 with 29.4 per cent of the vote.