Pressure for a national referendum on the Lisbon treaty intensified yesterday when a pressure group announced that more than 150,000 people took part in local ballots on the issue.

Votes in ten Labour and Lib Dem-held marginal constituencies organised by I Want A Referendum showed 88 per cent to be for a referendum and against the European Union treaty.

The results are perhaps unsurprising given that many treaty supporters refused to campaign but it is the turnout that will unnerve some ministers. The organisers appeared to have confounded predictions that the exercise would be a flop.

Between a fifth and a quarter of voters returned ballot papers in most areas of the ten constituencies in which the ballots were staged, including the seats of several ministers. According to the organisers, 152,520 voters completed their ballot papers across the ten constituencies. The polls were funded privately, at about £20,000 each.

In some areas ballot papers were sent to half the voters, because organisers were able to reach only those whose current details are published on the open electoral register.

Gedling, in Nottinghamshire, produced the highest turnout. There, 24,726 voters took part - 36.1 per cent of the electorate – on a par with some local authority elections.

In Bolton West, held by Ruth Kelly, the Transport Secretary, 28.1 per cent of voters took part. In Redditch, the seat of Jacqui Smith, the Home Secretary, the figure was 25 per cent. In East Renfrewshire, held by Jim Murphy, the Europe Minister, the turnout was 19.2 per cent.

Voting slipped to single figures in only one constituency, Hammersmith, where 5,685 people voted, or 7.8 per cent of the electorate. Organisers attributed this to fewer people listing their details on the open electoral register and a transient local population.

On Wednesday the Commons votes on a Conservative amendment seeking to authorise a referendum as part of the Bill ratifying the Lisbon treaty.

It is unlikely to be carried, with most Labour MPs opposed, although a rebellion by Eurosceptic backbenchers is expected. A group of Liberal Democrats is also expected to vote for a referendum, rebelling against a three-line whip to abstain. Nick Clegg, the party leader, will again try to force a vote on his alternative proposal for a referendum on EU membership. Last week the Speaker refused that.

I Want A Referendum will now press ahead with plans for more ballots, this time predominantly in marginal Lib Dem-held seats. This is partly in response to a backlash among Labour MPs at the involvement of the Labour backbenchers Frank Field and Kate Hoey in the campaign. Two others, Gisela Stuart and Graham Stringer, withdrew after pressure from Geoff Hoon, the Labour Chief Whip.

Bill Rammell, Labour MP for Harlow and Minister for Universities, attacked the ballot as unrepresentative. He told the Politics Show on BBC One yesterday: “Many people, myself included, made it perfectly clear we were having nothing to do with the referendum. Only one side of the argument was put and we end up, in my constituency, with a turnout figure, for the whole constituency, lower than any local government election, I’ve ever participated in.”

But Derek Scott, I Want A Referendum’s chairman and a former government economic adviser, said: “We’ve taken the most up-to-date and the only publicly available register there is and on that basis, it is a very substantial turnout.” Mr Scott defended the decision not to hold ballots in Tory-held seats, and said it was because “it’s the Labour and Liberal Democrat front benches that have broken their words” on holding a referendum.

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