EU commissioner blasts bilateral tax deals with Switzerland

"While member states are free to enter into international agreements, be they bilateral or multilateral, such agreements must not include any aspects which overlap with areas in which common action by the European Union has been taken or is envisaged," Semeta wrote.

A long-delayed revision of an EU savings law, which is still being blocked by Austria and Luxembourg, would widen disclosure requirements to bank accounts held by EU nationals abroad - for instance German and British nationals not paying taxes back home on their Swiss accounts.

"In this context, member states should refrain from negotiating, initiating, signing or ratifying agreements with Switzerland, or any other third state, insofar as any aspects regulated at EU level might be touched upon," the letter reads.

Germany and the UK have since agreed to re-negotiate the agreements and remove these provisions, but Bern has threatened to block other EU-Swiss agreements under way in retaliation. Switzerland is thought to view bilateral tax deals easier than having to deal a potentially more demanding EU pact.

Speaking at a press conference in Brussels on Monday, Semeta said he was "always in favour of a constructive approach in negotiations and I trust this will be the case."

"We have our reading of the agreements which says very clearly they have to be changed and that is what Germany and the UK are ready to do. It is up to Switzerland to decide what they will do, but I do not think we should take hostage other agreements currently being negotiated."

The commissioner, who wants to prevent other countries taking the London and Berlin route, also noted that over €1 trillion are lost yearly in the EU due to tax evasion and fraud, "a lot" given the current economic crisis. By unblocking the EU savings law, member states would be able to boost their revenues and make less painful cuts in the wages or pensions sector, he said.

Semeta's stance is backed by one of the key MEPs dealing with this dossier, British Liberal MEP Sharon Bowles who chairs the economics committee.

"When I first heard the proposal by Angela Merkel (on the bilateral agreement with Switzerland), my reaction was 'oh no' and it has not changed since," she said during the same press conference.

She insisted that bilateral deals can never be better than EU-wide agreements and said all member states should benefit from transparency and disclosure rules with Switzerland. "I believe in the supremacy of the community method," she said.

This article was corrected on 6 March to say that over €1 trillion are lost yearly due to tax evasion and fraud, not €3 trillion as it previously stated.