LONDON (REUTERS) - Former HBOS chief executive James Crosby said he has asked British authorities to remove his knighthood and will forego 30 per cent of his pension after being criticised for his role in the collapse of the British bank.

Sir Crosby's unexpected and extremely rare gesture came after a scathing report by British lawmakers on Friday which said there had been a "colossal failure" of senior management at HBOS, and put the blame on Sir Crosby and two other former bosses.

Sir Crosby stepped down as HBOS chief executive in 2006 and shortly after was awarded a knighthood, but the bank had to be bailed out by British taxpayers in 2008.

"In view of what has happened subsequently to HBOS, I believe that it is right that I should now ask the appropriate authorities to take the necessary steps for its removal," he said in a statement on Tuesday.

"I am deeply sorry for what happened at HBOS and the ensuing consequences for former colleagues, shareholders, taxpayers and society in general," he said.

Sir Crosby said he would forego 30 per cent of the gross pension entitlement payable to him during the rest of his lifetime, which amounts to 580,000 pounds (S$1.1 million) a year.

He would discuss with the pension scheme's trustees how the reduction would be implemented, and whether the amount waived should go to support good causes, or benefit shareholders.

He said the pension had been built up over his 30-year career, including 12 years at Halifax and HBOS, and was "entirely contractual in nature".

Since Friday's report, politicians have said the award should be cut or Sir Crosby should volunteer to reduce it.