By Jonathan Davies

MPs have called on HM Revenue & Customs to improve the time it takes to investigate and tax action against tax avoiders.

The Public Accounts Committee described HMRC's current performance as "unacceptably slow".

Margaret Hodge, chair of the committee, said "HMRC must do more, faster", explaining that tax revenues are at risk.

She referred to the story of a tax avoidance scheme which was closed down in 2009, but was only taken to a tribunal earlier this year.

Ms Hodge explained that the scheme, known as Liberty, may have resulted in £10m in lost taxes from 2,000 users.

"Although HMRC says Liberty was an exceptional case among the 750,000 personal tax return inquiries each year, it was unable to tell us how much delays had cost across the different tax avoidance schemes," she said.

The committee also called on HMRC to use new powers given by the government to tackle tax avoidance. It also criticised HMRC for failing to tackle businesses which used international tax structures to reduce their UK tax bill.

"Some international tax experts believe that the UK's tests for companies to gain tax residency are less rigorous than in other EU jurisdictions.

"Research into seven companies who have recently relocated to the UK for tax purposes showed very little inward investment was generated or jobs created in the UK in return for the tax benefits the companies receive," Mrs Hodge said.

"HM Treasury and HMRC should provide the committee with details of progress in identifying and addressing the ways that international tax structures are exploited, and set out the actual costs and benefits of recent changes to the UK's tax regime."

"Some international tax experts believe that the UK's tests for companies to gain tax residency are less rigorous than in other EU jurisdictions.

"Research into seven companies who have recently relocated to the UK for tax purposes showed very little inward investment was generated or jobs created in the UK in return for the tax benefits the companies receive," Mrs Hodge said.

"HM Treasury and HMRC should provide the committee with details of progress in identifying and addressing the ways that international tax structures are exploited, and set out the actual costs and benefits of recent changes to the UK's tax regime."