ZURICH (Reuters) – Offshore centres are rushing to sign data exchange tax deals with small Nordic countries such as Greenland to be taken off a "grey" list of tax havens, making a mockery of a Group of 20 (G20) bid to clamp down on evasion, campaigners said.

Earlier this month, the G20 summit named and shamed 40 or so countries, including major offshore centres Switzerland and Luxembourg, for not sharing bank data with foreign tax authorities.

They need to sign 12 tax treaties if they want to be upgraded to the "white" section of the list, compiled by the Organisation for Economic Co-operation and Development (OECD).

Since seven Nordic states have decided to negotiate tax treaties together, this is attracting scores of smallish offshore centres that wish to get off the hook.

"The number of treaties of course plays a role. If you can seal seven in one go that is attractive," Per-Olav Gjesti, deputy director general at the Finance Ministry of Norway told Reuters.

Bermuda, for instance, last week signed tax information deals with the seven Nordic economies, including Greenland and the Faroe Islands. This brings Bermuda's total to 11 treaties and so one step from removal from the grey list.

"There is no meaningful financial or trade movement with jurisdictions such as Greenland and the Faroe Islands," said David Spencer, an attorney in New York who is a senior adviser to the Tax Justice Network.

The Cayman Islands, another well-known offshore centre, signed treaties with the Nordic countries on April 1. The British Virgin Islands, popular among hedge funds, is lined up to clinch the Nordic tax deals in May and the Dutch Antilles and Aruba will follow suit in June, Mr. Gjesti said.

The British crown dependencies of Jersey and Guernsey and the Isle of Man all managed to sign a deal with the Nordic countries well before the G20 meeting and could therefore claim a place among the most tax-cooperative countries.

But Nordic countries have small populations and are known for strict tax policing, so these deals may not be significant in the global fight against tax evasion because they are unlikely to provide many customers for offshore centres, critics say.

Also, critics say the threshold of 12 treaties does not follow any logic and want pressure to continue on offshore centres even after they have obtained these agreements.

"By signing agreements with governments representing 0.43 percent of the world's population, Bermuda gets 66 percent of the way to international acceptability on tax," Richard Murphy, a chartered accountant and a campaigner against tax evasion, said on his Tax Research blog. "Which shows just how badly wrong the OECD got its tax haven listing."

The seven Nordic countries are home to less than 30 million people against a world's population of nearly seven billion.

Scandinavian states apply a system of automatic reporting of any information that holds tax value, so 80 percent of their citizens do not even have to file a tax return, Mr. Gjesti said.