Several lawmakers from British Prime Minister David Cameron's Conservatives will join the anti-EU UK Independence Party if he renews a coalition with the pro-EU Liberal Democrats, UKIP's leader Nigel Farage said.
Cameron, whose party has been in coalition with the Liberal Democrats since 2010, has promised a referendum on Britain's membership of the European Union by the end of 2017 if he is re-elected next month.
Two Conservative lawmakers defected to UKIP last year and several other eurosceptic members of Cameron's party were rumoured to be considering following suit at the time.
"There are Tory (Conservative) backbenchers who do not want a coalition again with Mr Clegg under any circumstances," Farage said in an interview in the Sunday Times newspaper.
"If Cameron comes back as prime minister in a coalition deal with Clegg and the terms of the referendum are on Clegg lines not Farage lines then you may very well see a more serious fracture in the Conservative Party," he said.
"They are terms which I find wholly unacceptable and all those Tory backbenchers would too," he added, predicting "more than a handful" would defect.
With most polls showing the Conservatives neck-and-neck with the opposition Labour Party ahead of the May 7 election, neither is expected to win a majority outright, leaving smaller parties vying to extract concessions in return for their support.
The Financial Times reported this week that Liberal Democrat leader Nick Clegg, who only favours holding an EU referendum if more powers are transferred to Brussels, could demand including under-18s and EU migrants in the vote in return for his backing.
UKIP, who are expected to win as many as six seats at the election, have said they will support a minority Conservative government in return for a referendum by the end of 2015.