Italy split spells setback for Berlusconi
The centre-right faction of Silvio Berlusconi has split, dealing another political setback to the former Italian prime minister.
Angelino Alfano, the deputy prime minister, said he and colleagues were forming a new centre-right party.
It comes as Berlusconi prepares to relaunch Forza Italia, the party that brought him to power two decades ago.
Tensions in Berlusconi's party have been high as he faces expulsion from parliament over a court conviction.
The BBC's Alan Johnston in Rome says Angelino Alfano has been Berlusconi's loyal right-hand man for years, and the defection is a major blow for the former leader.
However, it puts the fragile coalition of Prime Minister Enrico Letta in a slightly stronger position, he adds.
Berlusconi has argued that if he is expelled from parliament, his party should quit the coalition and that its cabinet ministers - like Mr Alfano - should resign and bring the administration down.
But Mr Alfano and others in the party have disagreed with that approach and the tensions surrounding the issue have now torn the faction apart, our correspondent adds.
One of the breakaway senators, Roberto Formigoni, told the LA7 TV network that Mr Alfano could count on 37 senators and 23 MPs for his new party.
Transport Minister Maurizio Lupi told reporters that the decision to split was taken with "great suffering" but that MPs could not join a Forza Italia of "extremists".
Last month, a leaders' meeting voted to suspend Berlusconi's People of Freedom Party (PDL) and restore the name - Forza Italia - used until 2007.
However, Mr Alfano and other PDL figures were absent from the vote, hinting at party divisions.
Earlier this month Berlusconi promised to topple the government by withdrawing the PDL's support - a move that prompted a confidence vote in the Senate.
But he was forced into an embarrassing climbdown when it became clear that several of his senators would back the government.
The media tycoon was convicted of tax fraud in October 2012 over deals his firm Mediaset made to purchase TV rights to US films. The sentence was upheld in August.
The Italian Senate will soon vote on whether to expel him, a move which would open up the risk of arrest over other criminal cases.