The OECD on Tuesday removed Costa Rica, Malaysia, the Philippines and Uruguay from its list of hard-line uncooperative tax havens after they bowed to pressure and vowed to open up their books.
"These four jurisdictions have now made a full commitment to exchange information according to the OECD standard," OECD General Secretary Angel Gurria told a press conference in Paris.
They were the only remaining countries on the first of three lists published after world leaders agreed last week at a G20 summit in London to crack down on tax havens.
One list named the four states the Organisation for Economic Cooperation and Development said had not pledged to accept international tax reporting standards.
A second "grey list" named 38 territories that had committed to such standards but had not yet fully implemented them, and a third list identified 40 countries that had substantially implemented them.
"I am happy that there is no longer any one of the 84 jurisdictions normally monitored by the OECD ... that is in the category of not adopting and having not committed to adopt the standards," said Gurria.
"This is very important progress," said the head of the Paris-based organisation that seeks to coordinate the economic policies of its 30 industrialised members.
Costa Rica, the Philippines, Malaysia and Uruguay are now on the "grey list."
"They have officially informed the OECD that they commit to cooperate in the fight against tax abuse, that this year they will propose legislation to remove the impediments to the implementation of the standard," the OECD said.
Tax havens have come under increasing scrutiny as the global financial crisis bites ever deeper, sparking calls for radical action to curb abuses blamed for the debacle, among them tax evasion and bank secrecy.
After US and European governments bailed out a number of banks, politicians began questioning how and why some of those same financial institutions were able to continue to operate in countries that encourage tax evasion.
Transparency International France last year estimated about 10 trillion dollars -- four times France's gross domestic product -- were stashed in secret offshore accounts away from the prying eyes of regulators or tax inspectors.
In the run-up to the G20 London summit, countries with long-held banking secrecy laws including Liechtenstein and Switzerland agreed to comply with regulation forcing states to share tax information.
Several countries protested after the publication of the latest lists, with some disputing their designation and others vowing to clear their names.
Swiss Foreign Minister Micheline Calmy-Rey said Tuesday that the OECD list had been based on political criteria.
"They don't have qualitative criteria to draw up these lists," she told reporters in Berne.
"My interpretation is that they had to have something concrete at the end of this G20 (summit)," she added. "But in reality, these criteria are political.
The only positive outcome of the G20 summit had been the commitment to set up a mechanism to monitor progress in this area, she added.
Switzerland has already protested at finding itself on the OECD's "grey list".
The OECD's "grey list" also included Belgium, Brunei, Chile, the Dutch Antilles, Gibraltar, Liechtenstein, Luxembourg, Monaco, Singapore and Caribbean nations such as the Bahamas, Bermuda and the Cayman Islands.
A third list of countries that have largely implemented internationally agreed tax standards includes Britain, China apart from its special administrative regions, France, Germany, Russia and the United States.