The Times has learnt that at least one FTSE 100 company is investigating domiciling itself outside the UK following an 18-month crackdown by Revenue & Customs on tax avoidance.

Other companies are so angry at the clampdown on previously accepted business practices that they are refusing to co-operate with Revenue’s attempts to understand corporate tax planning.

Guy Brannan, head of tax at Linklaters, the City law firm, said that the relocation plans of a number of companies were at a "pretty advanced stage".

Mr Brannan said: "The Government’s attitude is becoming counter-productive. If companies do not have to be headquartered in the UK and a large proportion of their business is elsewhere, they are investigating moving outside the UK." The Netherlands, Ireland and Luxembourg were popular alternatives to Britain, he said.

Other leading tax lawyers backed Mr Brannan’s claims that the Revenue’s anti-avoidance campaign had reached a pitch that could deter inward investment. Murray Clayson, global head of tax at Freshfields Bruckhaus Deringer, said that there had a been a "real acceleration in anti-avoidance law-making — 2005 had two Finance Acts, both of which contained significant attacks on corporate tax planning, as did the Pre-Budget Report before Christmas".

Patrick Mears, a tax partner at Allen & Overy, said: "The Treasury and Revenue have been going a bit too far. If they push it much further there’s a danger that people will actively look at repatriating outside the UK."

Mr Mears said the Revenue’s aggressive attitude had convinced companies not to assist the taxman’s attempts to understand modern business processes. "There’s an uneasy alliance between the main taxpayers and the Government — this is putting a strain on the relationship," he said.

The torrent of anti-avoidance legislation began in 2004, shortly after the Government introduced laws forcing companies to disclose how they minimised their tax bills. The disclosure regime is currently being extended, raising fears of even more stringent anti-avoidance rules.

Last November Ian McCafferty, the CBI’s chief economic adviser, attacked the Treasury’s anti-avoidance campaign. "These measures are effectively a covert means of extending the tax base to raise revenue while circumventing previously accepted tax principle and practice," he said.

A Treasury spokesman rejected the accusations. "We’re just collecting the appropriate amount of tax that Parliament has already set," he said. "The UK remains a very good place to do business."

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