LONDON (Reuters) - The leader of the Liberal Democrats accused the Conservatives of telling lies on Sunday in a referendum campaign on voting reform, his sharpest attack yet on his coalition partners that reflects strains in the alliance.
Lib Dems leader Nick Clegg said Conservative Prime Minister David Cameron was "defending the indefensible" by aligning himself with opponents of a change to a more proportional system in parliamentary elections, the subject of a May 5 referendum.
Clegg said the referendum's "No Campaign," supported by Cameron's centre-right party, was spreading "a headwind of lies, misinformation and deceit," as opinion polls point to a defeat for the proposed switch to the Alternative Vote (AV).
"This nasty No Campaign, I hope, will prove to be the death rattle of a right-wing elite, a right-wing clique who want to keep things the way they are," Clegg told the Independent on Sunday.
Simon Hughes, deputy leader of the Lib Dems, told BBC television he planned to report the "No Campaign" to the Electoral Commission watchdog for telling "untruths."
Analysts say there is little prospect of a split in the ruling alliance, but both sides are under pressure from grassroots supporters dissatisfied with the compromises of coalition to stress their differences ahead of the polls.
However, tensions have continued to rise between the Conservatives and Lib Dems ahead of a handful of polls next month in which Clegg's party is forecast to do badly.
Lib Dem support has plunged in opinion polls since they reneged on a promise to cut university fees, while Conservative supporters are unhappy the coalition has avoided a hard line on issues such as crime and European integration.
On Saturday Cameron appeared to contradict a policy announced by Clegg this month on the hiring of interns in government. The spat followed Cameron agreeing to delay public health service reforms following demands from Clegg.
Conservative Foreign Secretary William Hague dismissed the latest Lib Dem accusations as "excited" talk as feelings ran high ahead of the referendum. Away from the heat of the campaign the coalition continued to function well and would do so after the results were in, he said.
"A lot of these accusations are aimed at the No Campaign, rather than the Conservative Party. These things do get bandied about in a referendum campaign, feelings run high, people get excited," he told BBC television.
Voters will be asked to decide between the current first-past-the-post system and the AV in the May 5 referendum demanded by the Lib Dems for joining the larger Conservatives in a coalition government last year.
As well as the referendum, Britons will vote next month in regional elections in Scotland, Wales and Northern Ireland, and local authority elections in England.
Parliamentary election reform is a long-held ambition for the Lib Dems, who as Britain's third-largest party have been consistently squeezed by the current voting system.
In first-past-the-post system the single winner is the person with the most votes; there is no requirement to gain an absolute majority of votes.
Under the AV, each voter ranks candidates in order of preference so that if no single candidate gets a majority, votes are redistributed until one does.