Britain’s prime minister David Cameron and Chancellor of the Exchequer George Osborne have been urged by a charity to improve tax transparency in British Dependent Territories.

Save the Children said the UK Government should “consider hosting a meeting of crown dependencies and overseas territories ahead of the G8 Summit to encourage these jurisdictions to implement the new gold standard of beneficial ownership transparency in their own interests”, according to an article in Britain’s Guardian newspaper.

They were warned they are in danger of losing credibility on their central agenda for their G8 chairmanship this year if they do not unilaterally introduce greater tax transparency in British Dependent Territories such as the British Virgin Islands.

In a letter to Mr Osborne on Sunday, the leading aid charity Save the Children told the Chancellor he has the powers to impose tax transparency on territories.

The charity said there are fears that fresh exposures — including in the Guardian — about the scale of tax avoidance mean mr Cameron’s credibility on the issue needs shoring up.

In a speech in Davos in January, Mr Cameron promised to make tax transparency his number one goal for his G8 chairmanship.

In his letter Save the Children chief executive Justin Forsyth urged the government to “consider hosting a meeting of crown dependencies and overseas territories ahead of the G8 to encourage these jurisdictions to implement the new gold standard of beneficial ownership transparency in their own interests.”

Mr Forsyth added: “Tax haven secrecy facilitates tax evasion, corruption and undermines the ability of governments to mobilise revenue to invest in lifesaving essential services. This can be a life or death issue for the poorest children in the poorest countries”.

In the past, government ministers, including the former Labour home secretary Jack Straw, have made clear that the overseas territories and crown dependencies are sovereign jurisdictions and that the UK government does not have power to change their policies.

There is also a precedent for intervention. In the case of the Turks and Caicos Islands, due to endemic corruption on the islands the UK parliament passed new legislation in 2009 that suspended ministerial government and the house of assembly.