Anonymous has released a tape of the call in which detectives give details of alleged hackers being tracked.

The FBI said the information had been obtained illegally.

Later, it emerged Anonymous had also hacked the websites of US police forces and the Greek justice ministry.

The FBI said in a statement: "The information was intended for law enforcement officers only and was illegally obtained. A criminal investigation is under way to identify and hold accountable those responsible."

London's Metropolitan Police's central e-crime unit said the matter was being investigated but that no operational risks had been identified.

'Highly embarrassing'

Anonymous is a loose collective of "hacktivists" which has been responsible for cyber attacks on various companies, governments and individuals in recent years.

The recording of the conference call - said to have taken place on 17 January - was posted on YouTube, along with an email allegedly sent by the FBI to law enforcement agencies in various countries giving details of how to dial in to it.

It invited them to "discuss the on-going investigations related to Anonymous, Lulzsec, Antisec, and other associated splinter groups".

It was unclear how Anonymous obtained the recording, but a lawyer for one of the suspects discussed in it told the BBC it appeared to have been taken as an audiofile from an intercepted email, rather than having been eavesdropped on.

A comment on one of the Twitter accounts linked to Anonymous, AnonymousIRC, said: "The FBI might be curious how we're able to continuously read their internal comms for some time now."

The recording features about five men calling from the UK, Los Angeles and Washington, who discuss in detail the ongoing investigations into hacking and action being taken against suspects.

Among them are several British men accused of being behind cyber attacks in the US and UK.

The police give the online pseudonyms of suspects but the real names have been bleeped out of the recording.

When the British detectives discuss delaying some arrests while US investigations are being carried out, the FBI agent thanks them for their co-operation.

The British detective replies: "We're here to help. We've cocked things up in the past, we know that."

BBC security correspondent Frank Gardner says the recording will be highly embarrassing for the cyber crime detectives.

'More mayhem'

Later on Friday, Anonymous said it was behind an attack on a police website in the US city of Boston.

A message posted on the site before it was taken down said it had been targeted in response to "police brutality" towards the Occcupy Wall Street movement and warned there was "plenty more mayhem to deliver".

Meanwhile police in Salt Lake City, Utah are investigating a cyber attack on Tuesday on a site used by residents to report crimes.

The site was taken down and Detective Dennis McGowan said police were "knee deep in trying to get a feel for the extent of the problem".

Hackers operating under the Anonymous name also took over the website of Greece's justice ministry on Friday in a protest against the country's signing of a global copyright treaty and the government's handling of the economic crisis.

The website was replaced with a video of a figure wearing the symbolic white mask of Anonymous supporters, saying: "Democracy was given birth in your country but you have killed it."

報道稱，美英兩國最重要執(zhí)法部門之間的會議遭黑客竊聽，引發(fā)安全專家關(guān)注。安全風(fēng)險評估公司“Rapid7”的凱里說，執(zhí)法部門使用未經(jīng)加密的不設(shè)防渠道溝通，假設(shè)會議內(nèi)容涉及恐怖襲擊，竊聽者又是恐怖分子的話，后果將不堪設(shè)想。

據(jù)報道，這段長17分鐘，遭黑客公開的電話錄音中，可清楚地聽到FBI和蘇格蘭場探員討論針對黑客活動的調(diào)查進展，提到兩名被控的英國黑客，以及如何拖延聆訊過程以配合對方調(diào)查。會上探員說笑，如形容一名15歲英國黑客“有點白癡”，又互戴高帽，感謝對方協(xié)助辦案?！澳涿摺苯M織公布錄音時，將部分黑客真名做了消音處理。

除了錄音，“匿名者”組織還公開了會前4天FBI發(fā)給英國、法國、德國、愛爾蘭、荷蘭及瑞典執(zhí)法部門的邀請電郵。電郵寫有會議舉辦的時間以及登入密碼，相信“匿名者”就是藉此公然將會議進行錄音的。

FBI強調(diào)其本身系統(tǒng)并未遭入侵。局方消息透露，可能是接收電郵的歐洲執(zhí)法部門將電郵轉(zhuǎn)寄到不受保護的私人郵箱，因此遭黑客竊取。蘇格蘭場表示正調(diào)查此次事件，稱暫時無證據(jù)顯示遭入侵。

“匿名者”事后在社交網(wǎng)站“推特”(Twitter)上張貼錄音及電郵的鏈接，并發(fā)文稱：“FBI現(xiàn)在可能會很奇怪我們?nèi)绾文芤恢蓖德犓麄兊膬?nèi)部通訊。”有法國執(zhí)法部門消息稱，事件或?qū)е氯蘸髧H執(zhí)法部門更為謹慎，減少在電話會議上交換信息。