Bern - Switzerland sent a letter of complaint to the Organisation for Economic Cooperation and Development, posted on a government Website Wednesday, saying the think-tank did not receive its permission to publish a grey list of so called tax havens.

The OECD, which is supported a group of developed economies of which the Alpine nation is a member, placed Switzerland and several other countries on a grey list around the G20 meeting held in London at the beginning of this month.

Hans Rudolph Merz, the Swiss Finance Minister who also serves as president of the confederation, said he did not approve of the criteria for the list and the OECD should only take steps by consensus.

As Switzerland opposed the move, Merz said the OECD should have never published the names.

The letter to Angel Gurria, the head of the OECD, dated April 28, contained numerous questions, including one which asked "why are certain members of the G20 not included?"

Swiss officials have complained that some of the world's richest countries support havens or other systems to avoid paying taxes and yet only smaller countries appeared on the grey list.

Merz also noted that prior to the publication of the list, Switzerland had already agreed to accept the OECD standards for transparency and was in the process of renegotiating its bilateral double taxation agreements with several countries.

This week, US and Swiss tax officials met in Bern to begin such negotiations, though a second round will likely be needed to conclude the talks.

Switzerland, along with Lichtenstein, Luxembourg, Austria and some other countries, announced in the weeks leading up to the G20 that they would relax their banking secrecy rules to better combat tax fraud.

There had been rumours of a blacklist being drawn up of non- cooperative tax havens before the announcements were made.

Merz's letter was carbon copied to Alistair Darling, the British chancellor of the exchequer. (dpa)