George Osborne's opposition to a plastic bag tax is the last remaining barrier to the introduction of a levy in England, a Liberal Democrat in the Westcountry claimed as his party voted to bolster its "weaponry" against the Treasury's resistance.
The Lib Dem conference backed a motion demanding a levy on all single-use plastic bags, with proceeds to go to community food initiatives.
Andrew George, Lib Dem MP for St Ives, said the move was designed to counter what they said was a Treasury "log jam" which had repeatedly blocked the idea of charging for bags to encourage people to curb their use.
Mr George, the Lib Dem policy spokesman on the environment, said he hoped the adoption of a new party policy on the issue would place the issue back on the agenda.
"We have seen some indications of support coming out of Number 10," he said. "It has always been over-ruled by the Treasury. We have only one remaining log jam and we need to keep firing the most effective weaponry at it and making it quite clear that this issue will not go away."
However, Treasury insiders were said to be "bemused" by the suggestion that Mr Osborne was blocking the policy.
A poll by the Break the Bag Habit coalition of campaign groups last week found more than half people – 56 per cent – supported the idea of a small charge for disposable bags.
Official figures show around 350 million more bags were given out by retailers over last year, despite David Cameron demanding "significant falls".
Lib Dems say Caroline Spelman, the former Tory Environment Secretary, was supportive of the idea of a levy but came up against Treasury resistance, something the Treasury denies.