Pollster Peter Kellner said the figures show that "Britain's democratic system is in danger".

Nearly two-thirds of voters (62%) believe politicians lie "all the time" and less than a quarter (24%) think Parliament does a good job debating issues of concern to them, according to a survey released today.

Pollster Peter Kellner said the figures show that "Britain's democratic system is in danger".

In a lecture today the YouGov president will call for a new system of "people's vetos" under which voters can trigger a referendum to block measures passed by Parliament or by local councils.

But he will say that MPs and ministers should be banned from calling referendums which he described as the result of
politicians "losing their nerve".

Some 62% of more than 5,000 people quizzed for YouGov's survey on attitudes to British democracy agree that "politicians tell lies all the time and you can't believe a word they say", while only 24% say Parliament had done a good job in recent years debating issues of concern in a "sensible and considered way".

Delivering the Reuters Institute/BBC David Butler lecture in London this evening, Kellner will say that the findings reflect a growing public disdain for politicians, fuelled by modern communications technology which allows voters to access information and express their views in real time.

He will warn that public opinion is becoming a "superpower" and will caution politicians against the temptation to defer to voters by handing them the power to make important decisions through referendums.

"We are drifting towards a political system in which a combination of modern technology, mendacious journalism and angry voters will undermine representative democracy," Kellner will say.

"Referendums are not exercises in democratic purity but deeply flawed devices that we turn to when politics fails and politicians lose their nerve."

Kellner proposed that politicians should be banned from calling referendums. Instead, the public should be given the power to wield a "people's veto" on any Act of Parliament or local council decision by gathering the signatures of 10% of the electorate on a petition. The support of more than 50% of those registered to vote would then be required to overturn the measure, he said.