Campaigners against voting reform were last night accused of exploiting an election loophole to peddle "lies" about their opponents.
The acrimony surrounding the 5 May referendum on ditching the first-past-the-post system intensified as a publicity drive by the "No2AV" campaign was referred to the Advertising Standards Authority (ASA).
The controversy centres on adverts claiming that introducing the alternative vote for Westminster elections would cost the country £250m. The message is reinforced with images of a baby in intensive care – saying the cash should be spent on a cardiac facility – and of a soldier – saying the £250m would be better spent on bulletproof vests. Polls conducted since the campaign was launched suggest that support for moving to the alternative vote has fallen.
A spokesman for the Yes campaign said: "These shameful adverts are based on a lie. The No campaign can't defend the current voting system, so instead is peddling messages it knows not to be true."
Despite the referral to the ASA – by the left-wing blogger Sunny Hundal – it appeared last night that there was no sanction over the content of material put out during the referendum campaign.
A spokesman for the ASA told The Independent it had no remit over political advertising, which it said was regulated by the Electoral Commission.
But the Electoral Commission said it only regulated political funding and at first referred concerns over referendum publicity material to the ASA. It later said only adverts that were defamatory or stirred racial hatred could face action.
Mr Hundal said: "I made the complaint because it is obvious to everyone, including many who oppose the AV, that the £250m figure is deeply dishonest. But additionally, it highlights the fact that there seems to be no way to ensure such third-party political ads stick to the facts.
"A group that isn't revealing its funders is investing thousands of pounds in ads that have little basis in reality. Others could follow their lead in the future to smear political opponents too. Who would regulate that?"
The No campaign said it had no regrets over its advertisements, which it said struck a chord with voters witnessing heavy spending cuts in their communities. It explained that the £250m figure was calculated from the £150m price of electronic machines to count votes cast under the AV system, the £82m cost of holding the referendum and a further £20m-plus expense of publicity campaigns to explain AV if the voting system is changed.
A spokesman said it would, if required, be able to provide clear and detailed explanations of how the figures were calculated.