VILNIUS (Reuters) - The European Commission rebuffed on Saturday an EU legal opinion that questioned the legality of a planned financial transaction tax and said work on the levy in 11 European Union countries would go on. The legal services of the European Council, the institution which represents governments of the 28-nation EU, said in their 14-page legal opinion dated September 6 that the Commission's transaction tax plan "exceeded member states' jurisdiction for taxation under the norms of international customary law". European Union finance ministers discussed the financial transaction tax briefly on Saturday, with the Commission saying there was a misunderstanding on the opinion. "We are confident that the Commission's arguments and arguments of the legal service of the Commission will demonstrate very clearly to our member states that the approach which has been taken in the proposal is the correct one and does not breach any provisions of the Treaty," European Commissioner Algirdas Semeta, who is responsible for taxation told reporters. Germany, France, Italy, Spain, Austria, Portugal, Belgium, Estonia, Greece, Slovakia and Slovenia were planning to adopt the tax on stocks, bonds, derivatives, repurchase agreements and securities lending. Semeta said first reading of the proposal by the member states was already concluded. "I believe that we will present arguments to our member states for the next meeting of the Council working group. So the work is in progress and I do not see any reasons to stop this work or to make some additional reflections," added Semeta. Britain, the bloc's largest financial center, and 15 other EU member states refused to support the transaction tax proposal raising questions about how it would work with only some members participating. (Reporting by Martin Santa; editing by James Jukwey)