LONDON (Reuters) — One in five British companies has relocated some of their activities overseas and a third are considering it because of gripes over tax, according to a Confederation of British Industry poll published yesterday.Britain’s biggest business lobby group said its survey of 87 companies showed 71 percent wanted lower corporation tax, as it began its annual two-day conference a week before Chancellor of the Exchequer Gordon Brown’s pre-budget report on December 6.

“Our survey shows that business leaders believe the UK’s corporate tax regime is more burdensome than it was five years ago, and that this is making the UK less attractive as an international business location,” said CBI Director General Richard Lambert.

The survey also showed nearly 20 percent of companies had considered moving their headquarters abroad.

The CBI called on Brown to cut companies’ tax bill by $2 billion ($3.9 billion) in 2007/08 and then repeat the reduction annually to achieve a cut in the corporation tax rate to 25 percent by 2011 from 30 percent now.

Two Lloyd’s of London underwriters, Hiscox and Omega, are in the process of redomiciling to Bermuda, in part because of Britain’s tax and regulatory burden. A third, Catlin, moved last year.

Prime Minister Tony Blair announced plans to cut the regulatory burden on companies by a quarter when he addressed the CBI conference for the last time yesterday.

“In the next few weeks we will be setting out plans for government departments to take a 25 percent cut in the burden of regulation,” Blair said.

“I think it’s important we go through this item by item,” he said, adding the government would work closely with business to push though the changes.

Brown, who is expected to take over from Blair within a year, will address the CBI conference today, when he will seek to reassure firms that he is listening to them.

But government sources say big changes in headline tax rates are very unlikely in the pre-budget report.