LIBERAL Democrat campaigners have been privately advised to "squeeze" the Greens to try to prevent them from unseating LibDem politicians.

An internal LibDem election manual obtained by the Sunday Herald brands the Greens as politically "dangerous" because of their ability to win votes from LibDem supporters.

One way of attacking the Greens is to link them to extremists like the animal liberation movement, the manual says. It proposes tactics designed to deprive Greens of the "oxygen of publicity".

The manual was produced in 2006 by the UK Association of Liberal Democrat Councillors, and was circulating among activistsattheLibDem'sScottish Conference in Aviemore in February. The 20-page document suggests that LibDems sometimes fear the Greens more than Labour, the Conservatives or SNP.

"They should be squeezed as hard - if not harder - as your other opponents," it advises. "If you are likely to face a major challenge from the Green Party, then you should include graphs showing them in third/fourth place on all your leaflets. You should also use this squeeze message in letters to voters."

Campaigners are encouraged to "make a particular effort to squeeze" identified groups of potential Green voters. "Stop them before they win a seat," it advises, because once parties get established "they can be very hard to shift".

To the Scottish Greens, the manual is evidence that the LibDems are "rattled". They point out that the most recent opinion poll in Scotland shows the Greens just a point behind the LibDems.

"We're disappointed to discover there's an official LibDem manual on how to smear the Greens, and we certainly recognise a lot of their tactics from it," says Mark Ruskell, Scottish Greens election campaign director. "We're advising our candidates to stick to the issues, and to push the LibDems hard on their record of failure in government."

A spokesman for the Scottish Liberal Democrats in Edinburgh had not seen the manual, but was sure there would be other versions advising on how to combat other parties.