To the embarrassment of US politicians who have been excoriating so-called tax havens such as Switzerland, the tiny US state of Delaware has been dubbed the world’s most secretive tax location, according to a ranking of financial centres by a new report.

A survey of 60 financial jurisdictions by the Tax Justice Network, a left-wing lobby group which campaigns against tax evasion and tax avoidance, said Delaware was found lacking in 11 out of 12 secrecy indicators. London was also ranked in the five most secretive jurisdictions.

On its website, the TJN says it “promotes transparency in international finance and opposes secrecy. We support a level playing field on tax and we oppose loopholes and distortions in tax and regulation, and the abuses that flow from them. We promote tax compliance and we oppose tax evasion, tax avoidance, and all the mechanisms that enable owners and controllers of wealth to escape their responsibilities to the societies on which they and their wealth depend”.

In recent months, bankers in Switzerland’s financial industry, for example, have accused countries such as the UK and US of hypocrisy over their criticisms of tax havens, pointing out that both nations operate tax havens themselves.

While some groups such as TJN attack tax evasion and even tax avoidance – the latter is not a crime in countries such as the UK – other groups say tax havens provide an important benefit for the world economy by pressurising governments into keeping taxes lower than would otherwise be the case. The Washington-based Cato Institute, for example, has defended what it calls tax competition between jurisdictions.

The TJN’s report says Delaware, home to half of all America's quoted companies, fails to place on public record details of trusts, company accounts and, crucially, the identity of beneficial owners – the people who receive the profits. It also allows companies to relocate to other countries, leaving minimal trace.