The leader of the Liberal Democrats in Northumberland last night said a deal between his party and schools campaigners was done behind his back.

Last week, the K3 group of parents opposed to Northumberland County Council's plans for middle schools announced that it had merged with the Liberal Democrats to present a joint opposition to the plans.

But now the Liberal Democrat group leader on the council has revealed that the "merger" had been negotiated without him or the majority of Lib Dem councillors knowing anything about it.

In an admission that will throw the campaign into chaos Berwick councillor Scott Weightman said he only found about the deal when he returned from holiday to read about it in The Journal.

And he said that far from being opposed to plans for schools re-organisation, his group on the county council was evenly split between those for and those against the plans. His comments put in doubt the K3-Lib Dem alliance, though former K3 members have insisted they will still be standing as Lib Dems when candidates are unveiled later this week.

Coun Weightman said: "The situation is a total surprise to me. I've phoned several of the other Liberal Democrat councillors and they know nothing either.

"Any group is entitled to put up candidates but this is something I just wasn't aware of. I had been away over the Easter holidays and the first thing I knew about it was when I read it in The Journal."

K3 made the surprise decision to disband and join the Lib Dems last week after the Liberal Democrat manifesto said the party was opposed to the county council's Putting the Learner First strategy. That programme proposes closing middle schools and setting up a system of primaries and secondaries to free up resources and be more in tune with the National Curriculum.

The plans have angered a large number of parents, and a number of Liberal Democrats - led by Morpeth councillor and Hexham parliamentary candidate Andrew Duffield - tried to harness that opposition for the Lib Dems.

Coun Duffield has been summoned to a group meeting later this week to explain his part in negotiations with K3, but last night denied he had gone behind colleagues' backs.

He said: "This all happened in the space of a week. Scott was away on holiday so I spoke to the deputy leader but it wasn't possible to contact all of the other councillors in that time."

Former K3 chairman John Harrison insisted he would still be standing as a Liberal Democrat at local elections due on May 5.

He said: "When the Liberal Democrats published their manifesto last week, their position on education was very similar to ours. Unless they're withdrawing that - and I don't think they are - we're very happy to sign up to it."