Business For Britain said its analysis of Government impact assessment showed net costs to UK firms of laws be attributed to the Lisbon Treaty amounted to £12.2bn. The majority could be attributed to green laws brought in under the treaty, enacted in 2009, the group found.
The most expensive law requires car manufacturers to comply with EU emissions standards and has cost British companies £7.4bn, the analysis showed. Laws requiring firms to reduce greenhouse gas emissions have so far cost firms £3bn.
Meanwhile, harmonisation of components that go into motor vehicles has cost UK businesses £294 million while standardisation of battery production has cost £40m, the campaigners said.
The group claimed the final cost to businesses was estimated to be £96.5bn.
Matthew Elliott, Business for Britain's chief executive, said: "Our research makes a compelling case for the Government to use the forthcoming renegotiation to reverse some of the most expensive provisions of the Lisbon Treaty."
Research for British Influence indicated trade with the EU was worth £207bn a year to the UK. Peter Wilding, director of British Influence, said: "Almost 85% of the £12bn potential costs identified by Business for Britain would come from efforts to reduce CO2 emissions. The UK has often set stricter targets for itself than the EU so we may well have these types of rules regardless."