Come clean on Lib Dem links, vote group told

The call comes from the "No to AV" group which claims many of its opponents in the "Yes to Fairer Votes" camp are former Lib Dem candidates or have worked for the party.

It is also claimed the Lib Dems have asked for donations to their party using literature featuring the same "Yes to Fairer Votes" slogan as the campaign.

The "No" campaign points to research showing the Lib Dems would increase the number of seats they have at Westminster under an Alternative Vote (AV) system.

This is the real reason why a change to the electoral system is so strongly supported by the Lib Dems, they claim.

A dossier released by the "No" campaigners claims five out of six of the "Yes" campaign's steering committee have worked for or "explicitly supported" the Lib Dems in the last 12 months and that at least half of their grassroots co-ordinators are former Lib Dem candidates, councillors and activists.

So far, the "Yes" camp has mainly used as its frontman Jonathan Bartley, a father who confronted David Cameron during the election over his claims that the Tories would increase the segregation of disabled children in schools.

Their campaign has not involved high-profile politicians, instead using "ordinary" people to make their case.

In contrast the "No" camp has lined up a cross-party campaign of political big hitters, including Labour former cabinet ministers Lord Prescott, Lord Reid, David Blunkett and Lord Falconer.

They will work alongside senior Tories such as Foreign Secretary William Hague, Justice Secretary Ken Clarke and party chairman Baroness Warsi.

But the campaign suffered embarrassment after it was first forced to remove Education Secretary Michael Gove from its list of supporters and then wrongly claimed he was opposed to the switch to AV.

Labour promised a referendum on AV in its manifesto and the change is supported by new leader Ed Miliband, but MPs have a free vote on the issue and there is significant internal opposition.