"We work on the assumption that one or more entities may be listening to our conversations," the watchdog International Atomic Energy Agency'sspokesman Mark Gwozdecky said.

"It's not how we would prefer to work but it is the reality. At the end of the day we have nothing to hide," Gwozdecky said.

Iran meanwhile, accused the United States of violating international law by allegedly listening in on telephone calls between ElBaradei and Iranian diplomats.

Government spokesman Abdollah Ramazanzadeh claimed the conversations did not even merit being bugged given that nothing secret was ever discussed with ElBaradei.

But he added "this is not the first time we have seen the United States violate international rules".

US President George W. Bush's administration has listened in on phone calls between ElBaradei and Iranian diplomats, seeking ammunition to oust ElBaradei as head of the IAEA, The Washington Post alleged Sunday.

"The intercepted calls have not produced any evidence of nefarious conduct by ElBaradei," the Post said, quoting three unnamed US officials who had read the transcripts.

The United States wants the IAEA to report Iran to the UN Security Council for possible sanctions over what Washington says is its covert nuclear weapons program.

But ElBaradei says the "jury is still out" on whether Tehran's program is peaceful or not.

The Egyptian diplomat, 62, also earned the ire of Washington by questioning US intelligence on Iraq. The Bush administration opposes a third term for ElBaradei in 2005 as IAEA chief.

The official US position is that heads of international organizations should not serve more than two terms, as ElBaradei will have done by next year.

ElBaradei had on December 4 angrily denied charges he had collaborated with Iran ahead of publishing written reports on his investigation of the Islamic Republic's controversial nuclear program.

"We never show a report to any single member" of the IAEA, "not the least of course an inspected country," ElBaradei told AFP in a telephone interview.

He also said it was a "gutter accusation" to accuse him of an Islamist bias, adding that whether a country he works on "is Muslim or Buddhist makes not an iota of difference," especially since IAEA reports are a "collective process" involving international teams of experts.

A US official has told AFP that a draft copy of the September IAEA report was actually given ahead of time to the Iranians, in order for them to suggest changes, in comments echoed by a diplomat from another IAEA member country.

ElBaradei also characterized this as a "gutter accusation."

"We don't leak to any single person outside the 10 or 20 people who are involved in the process," of drafting reports at IAEA headquarters in Vienna, ElBaradei said.

The IAEA has issued seven written reports on Iran in an investigation which began in Febuary 2003. The reports are filed ahead of IAEA board of governors meetings that decide how tough the agency will be on Tehran over its nuclear program.