A parliamentary drive to force greater transparency on the UK's offshore tax havens is being led by former Commons spending watchdog chairwoman Dame Margaret Hodge and ex-international development secretary Andrew Mitchell.
The pair, backed by scores of MPs from across the Commons and supported by an alliance of charities, are tabling an amendment to legislation currently going through the Commons that would mean much greater information on company ownership would be published in the UK's overseas territories as part of the effort to clamp down on tax dodging.
The amendment to the Criminal Finances Bill would require overseas territories to establish public registers of the beneficial ownership of companies in order to reveal who is really behind firms based offshore.
Labour's Dame Margaret led investigations into corporate tax dodging as chairwoman of the influential Commons Public Accounts Committee.
Her amendment is signed by 80 MPs from across the Commons, including Tory former Cabinet minister Mr Mitchell.
Charities and campaigners including Christian Aid, Save the Children, Global Witness, Transparency International, ActionAid and Oxfam also back the move.
The legislation is set to be debated in the Commons early in the New Year.
Although many overseas territories have established registers of beneficial ownership, they have not been required to make them publicly available.
Oxfam's head of campaigns Sally Copley said: "The Government is undermining its own laudable fight against poverty by allowing UK-linked tax havens like Bermuda to facilitate tax dodging that starves the world's poorest countries of tax receipts needed to pay for schools and hospitals.
"These tax transparency standards are essential to hold the overseas territories accountable for their policies' impact on other countries - especially the poorest, which are hardest hit and have the most to lose from tax dodging."
Dame Margaret said: "The Government has published the Criminal Finances Bill to try and tackle corruption. While it includes some important and welcome measures, it is astonishing that the bill doesn't even mention the UK's tax havens.
"The MPs supporting my amendment are saying that the Government can't possibly claim to be tackling corruption without getting a grip on the tax havens that are under the UK's umbrella which facilitate all kinds of corruption and tax avoidance and evasion right across the world.
"Over half of the corporate entities exposed by the Panama Papers were registered in the British Virgin Islands (BVI). BVI is a British Overseas Territory. The UK is at the centre of a global web of tax havens which are costing UK taxpayers and developing countries huge sums of money."
Then prime minister David Cameron asked the overseas territories to consider adopting the same level of transparency as the UK over three years ago but there had been "dither and delay" on the agenda, Dame Margaret said.
Sutton Coldfield MP Mr Mitchell said: "I hope this amendment will help the UK Government to persuade the overseas territories to adopt the same level of transparency as the UK.
"This is so important for people in developing countries who are losing out due to tax dodging. For example, Africa is actually a net creditor to the world. I encourage other Conservative MPs to support the amendment, and I hope the Government will support it and ensure transparency in our overseas territories."
A Government spokeswoman said: "The UK is at the forefront of international efforts to increase corporate transparency and tackle tax evasion and corruption and was the first G20 country to commit to establish a public register.
"The steps overseas territories and Crown dependencies are taking on beneficial ownership transparency and tax transparency will put them ahead of most other nations.
'We are aware of the amendment that is being tabled on this issue and will provide a formal response at Report stage of the Bill.'"