The number of requests for information by the UK tax authority made to crown dependencies and overseas territories on possible tax evaders reached a record high during the past year, as the UK government continued its crackdown on offshore tax havens, according to the latest research from international law firm Pinsent Masons.

HM Revenue and Customs made 72 requests for financial data to offshore tax havens such as Jersey, Bermuda and the Cayman Islands in 2012, up 26 per cent from 2011 and more than double the number made in 2010.

"This will send shivers down the spine of those individuals and business with any undisclosed assets in places like Bermuda and the Cayman Islands. HMRC is closing the net and will come down heavily on those not paying tax, so individuals and businesses with money sheltered offshore should get on the front foot before HMRC finds out and begins an investigation," said Reg Day, director at Pinsent Masons.

The UK’s crown dependencies and overseas territories have been under increasing pressure from the UK government to start co-operating more closely with the HMRC in order to root out tax evaders.

Under proposed tax compliance information sharing arrangements, HMRC will soon be able to obtain greater levels of information about bank accounts held by UK taxpayers in the crown dependencies and overseas territories automatically.

In May, all crown dependencies and overseas territories with significant financial centres announced a commitment to tackle tax evasion with the aim of setting a new standard of international tax transparency.

Anguilla, Bermuda, the British Virgin Islands, Montserrat and the Turks and Caicos Islands, all agreed to share information, following a similar agreement recently signed by the Cayman Islands.

Under the agreement, much greater levels of information about bank accounts will be exchanged bilaterally with the UK and multilaterally with the "G5", which comprises the UK, France, Germany, Italy and Spain. This includes names, addresses, dates of birth, account numbers, account balances and details of payments made into those accounts. The deal also includes information about entities such as trusts.

Many offshore tax havens have also agreed to sign up to the Multilateral Convention on Mutual Assistance, a protocol developed by the Council of Europe and the Organisation for Economic Cooperation and Development that facilitates cooperation between states on tax matters.