A campaign group which helped force the government into an embarrassing U-turn over plans to sell off forests has set its sights on stopping a planned cull of badgers.

The government announced earlier this month that it would press ahead with issuing licences to shoot the wild animals in an effort to eradicate bovine tuberculosis from cattle herds, a disease which is costing farmers millions of pounds.

The move has attracted criticism from animal rights groups and others after it was reported that the government's own advisers warned it may not be effective.

Now the campaign group 38 Degrees, which got 532,000 people to sign its Save Our Forests petition to derail the coalition's woodland sell-off earlier this year, has joined those fighting the cull.

The group questions whether a cull is the most effective way of tackling the spread of bovine TB, with 87% of members polled saying they should oppose it. More than 13,000 people have signed a petition in the last few days.

Writing on the group's blog, campaigner Marie Campbell wrote: "Some of us believe killing badgers would be wrong under any circumstances. Some of us believe that if the science really proved that shooting badgers could make a real dent in the cow TB problem, it would be a tragic necessity.

"But 87% of us agree on this: the government's current plans to shoot England's badgers simply don't stack up. The government's own scientific advisers warn that it won't solve the problem of TB in cattle, and could even make it worse."

The environment secretary, Caroline Spelman, who shouldered much of the blame for the U-turn over forests, launched the badger cull on 19 July, saying bovine TB would cost farmers in England alone £1bn over the next decade if action was not taken.

The Department for Environment, Food and Rural Affairs (Defra) claims that nearly 25,000 cattle were slaughtered in England in 2010 because of the disease, costing the country £90m.

It is especially a problem for farmers in the west and south-west of England, with Defra claiming 23% of cattle farms in these areas were unable to move stock off their premises at some point in 2010 due to being affected by the disease.

There is a vaccine that could be used to halt its spread but Spelman said there were "serious practical difficulties" with it.

"This terrible disease is getting worse, and we've got to deal with the devastating impact it has on farmers and rural communities. There's also the effect on the farming economy and taxpayers," she said.

"We cannot go on like this. Many farmers are desperate and feel unable to control the disease in their herds. And we know that unless we tackle the disease in badgers we will never be able to eradicate it in cattle.

"We are working hard to develop a cattle vaccine and an oral badger vaccine, but a usable and approved cattle vaccine and oral badger vaccine are much further away than we thought and we can't say with any certainty if and when they will be ready. We simply can't afford to keep waiting."

An early day motion opposing the cull and asking Spelman to rethink the plans, tabled by Newport West Labour MP Paul Flynn in March, has so far been signed by 82 MPs. The majority are Labour and Liberal Democrats, with Peter Bottomley (Worthing West) the sole Conservative MP to sign it.