HMRC has dramatically scaled down the volume of requests it makes for information on individuals' tax affairs.

Double taxation agreements aim to stop an individual's income being taxed in two separate countries, but they also empower tax authorities to unearth the value of assets held by individuals overseas.

Under its double taxation agreements with other countries, the taxman made 640 requests in 2011-12, some 40% less than the 857 made in the previous financial year, figures from law firm Pinsent Masons reveal.

Phil Berwick, a partner at the firm, said: 'Many potential targets might be coming forward voluntarily, saving the HMRC from launching an investigation. HMRC's recent tough approach has prompted people on to the straight and narrow.'

He hinted that the fall may also be down to staff shortages at the department, which has seen employee numbers slashed to the extent that it will have 44% fewer workers in 2015, than it did in 2005.

'It may be the case that HMRC's heavy workload is catching up with it,' Berwick added. 'The recent National Audit Office report on HMRC's compliance performance revealed that HMRC had 41,000 open avoidance investigations. HMRC has pushed very hard on compliance recently and may be hitting capacity'.

HMRC boasts one of the world's largest networks of Double Taxation Agreements and Tax Information Exchange Agreements, with agreements to share individuals' tax data with over 100 other countries.

In 2011, HMRC made 96 requests to Australia, 49 to Spain and 38 to Ireland.

An HMRC spokesman, said: 'The number of requests in respect of individual taxpayers will vary naturally from year to year in response to a number of factors. HMRC is in fact putting more resource into countering avoidance and evasion, not less.

'Our sources of information on overseas accounts are increasing all the time so the net is closing on all tax cheats who try to hide their assets offshore. We are using all the technology, data and skills at our disposal to tackle those who engage in offshore evasion.

'The government has made £77m available to tackle the minority who refuse to play by the rules so if you have been hiding money off shore to evade tax, it is only a matter of time before we find you.'