The Netherlands, Switzerland and Ireland are among the world's most damaging corporate tax havens, according to a new report by Oxfam.
Oxfam researchers said governments around the world are slashing corporate tax rates and allowing "extreme forms of tax dodging" in order to attract investment.
They warned that this race to the bottom is "starving countries out of billions of dollars needed to tackle poverty and inequality."
Oxfam ranked the countries by looking at their tax rates. They also considered whether the countries offer unfair tax incentives, and whether they cooperate with international efforts to curb tax avoidance, for example by agreeing to increase financial transparency.
It said Bermuda was the worst, with Cayman Islands second to worst and the Netherlands third.
In response, the Bermuda Business Development Agency said the report ignored the island nation's unique trade and finance structure was based on "flawed economics and lack of understanding."
Related: How Apple paid just 0.005% tax on its global profits
Oxfam argues that when governments slash corporate taxes, they have to balance their books by reducing public spending or by raising other forms of taxes, such as VAT.
"Ordinary people -- particularly the poorest -- are paying the price for this reckless competition through increases in personal taxes and cuts to essential services, such as healthcare and education," said Esme Berkhout, Oxfam's tax policy adviser.
Oxfam said its analysis showed that 90% of the world's biggest companies had a presence in at least one tax haven.
Related: The murky world of offshore tax havens
Several of the countries named by Oxfam in the report have been involved in tax scandals featuring some of the world's biggest companies.
Ireland was ordered by the European Union in August to recover up to €13 billion ($13.7 billion) in unpaid taxes from Apple.
Thanks to its arrangement with Ireland, Apple (AAPL) paid only 1%, or less, tax in the country, well below the 35% top rate of corporate tax in the United States and Ireland's 12.5% rate. Ireland was named sixth worst corporate tax haven by Oxfam.
Starbucks (SBUX) was told last year by the EU to pay back up to €30 million it saved thanks to a sweetheart tax deal with the Netherlands. Fiat Chrysler (FCAM) was ordered to repay a similar amount after a similar deal with Luxembourg.
Bahamas, which is ranked 11th and British Virgin Islands, ranked 15, were both named among offshore tax havens used by Mossack Fonseca, the law firm at the heart of the Panama Papers tax avoidance scandal.
The European Union, the G20 and the OECD have all stepped up their efforts to close corporate tax loopholes in the past year, but Oxfam is saying a lot more has to be done.
"Governments must work together to stop this crazy race to the bottom on corporate tax and ensure companies pay their fair share," said Berkhout.
Related: New crackdown on corporate tax avoidance
Here is the list of the world's worst tax havens, according to Oxfam:
1. Bermuda
2. the Cayman Islands
3. the Netherlands
4. Switzerland
5. Singapore
6. Ireland
7. Luxembourg
8. Curacao
9. Hong Kong
10. Cyprus
11. Bahamas
12. Jersey
13. Barbados
14. Mauritius
15. British Virgin Islands
Oxfam also pointed out that while the U.K. doesn't appear on the list, four of its territories do: Cayman Islands, Jersey, Bermuda and the British Virgin Islands.
