The Attorney General Lord Goldsmith says he now favours allowing intercept evidence to be used in court.
He told the BBC he thought it would increase the chances of jailing crime bosses and terrorists.
He had been persuaded of the benefits by seeing how the US had used intercept evidence to jail five top Mafia bosses.
The Tories, Lib Dems and civil liberty groups have long backed such a change, but security services fear it will let criminals see how they operate.
Lord Goldsmith told BBC Radio 4's Today: "We do have a need to use intercept in court if we're going to give ourselves the chance of convicting some of the most dangerous and prolific criminals in the country.
"It is a vital tool therefore for organised serious crime - this is what I've been told particularly by colleagues in the United States - and for terrorism.
"But there are legitimate concerns which particularly the security services have."
He said those concerns included protection of sources and methods of working, and also fears that the security services may get "swamped" by defence teams' demands for transcripts of hours and hours of bugged conversations.
"We have to work together, and work hard together to find ways to deal with those problems and those legitimate concerns," he added.
Opposition parties and civil liberty groups have long backed the use of intercept evidence in court.
They say it would make it easier to bring terror suspects to court and reduce the need for control orders - which are used for people who are suspected of being involved in terrorism but where there is not enough permissible evidence to bring them before a court.
The chairman of the joint Commons and Lords Committee on Human Rights, Labour MP Andrew Dismore, told Today: "Our view is that it is vital that such evidence should be brought before the courts.
"What we have certainly found from our inquiry was that intelligence services around the world, prosecution services around the world, simply could not understand why this vital evidence was not available to our courts."