Rich countries should end their financial support for corrupt governments and blacklist companies that get caught paying bribes abroad, a watchdog group that monitors corruption in 133 nations said Tuesday.

Half of developing countries suffer from "a high level of corruption," and some wealthy nations fare little better, according to surveys of business people, academics and risk analysts by Transparency International.

Bangladesh (search) came in last, at 133, trailed by Nigeria (search) and Haiti (search) as the three most corrupt countries, according to the 2003 Transparency International Corruption Perceptions Index.

Rated number one, or least corrupt, was Finland, followed by Iceland and, in a tie for third, Denmark and New Zealand. The United States was 18 on the list, tied with Ireland.

"Rich countries must provide practical support to developing country governments that demonstrate the political will to curb corruption," Transparency International chairman Peter Eigen said in a statement.

Donor countries and international financial organizations should take "a firmer line" by cutting financial aid to corrupt governments and punishing companies that pay bribes, he said.

The watchdog group's latest survey noted corruption in rich countries too. Levels of corruption are "worryingly high" in Greece, number 50 on the list, and Italy, ranked 35th, said Laurence Cockcroft, the head of Transparency International in Britain.

Several potentially wealthy oil-producing countries stood out for poor scores on the corruption index. Angola, Azerbaijan, Indonesia, Libya, Venezuela and Kazakhstan all ranked among the most corrupt 25 percent of countries surveyed.

Transparency International called on international oil companies to disclose the payments they make to governments and state-run oil companies, as a way to ensure that the wealth of energy-rich countries benefits more of their citizens.

Disclosure of such payments would discourage recipient governments from wasting their oil earnings on "expensive vanity projects" or stashing the funds in secret offshore bank accounts, Cockcroft said.

Other non-governmental groups such as Britain's Global Witness have called before for a public disclosure of oil company payments, but their demands have had little effect so far.

When the oil company BP PLC revealed it had paid a bonus of $112 million for the right to drill in Angola, that country's national oil company, Sonangol, threatened to revoke BP's exploration contract.

Other international oil companies, apparently fearful of jeopardizing their own business opportunities in Angola, have been reluctant to follow BP's example.