VIENNA (Reuters) - Major powers closed ranks on Thursday to increase pressure on Iran to address fears about its atomic ambitions, and the U.N. nuclear chief said it was his duty to "alert the world" about suspected Iranian efforts to develop atom bombs.
The six powers involved in diplomacy on Iran -- the United States, Russia, China, France, Britain and Germany -- overcame divisions exposed by a hard-hitting U.N. nuclear report on Iran last week and presented a united front towards Tehran.
They hammered out a joint resolution in intense negotiations and submitted it to the 35-nation board of the International Atomic Energy Agency (IAEA), a Vienna-based U.N. body, which is expected to debate and vote on it on Friday.
But it will not satisfy those in the West and in Israel, Iran's arch-enemy, who had hoped IAEA head Yukiya Amano's document would trigger concrete international action to rein in Tehran, such as an IAEA referral of its case to the U.N. Security Council.
Last week's IAEA report, which assessed that Iran has been conducting research and experiments geared to developing a nuclear weapons capability, has stoked tensions in the Middle East and raised a clamour in Western capitals for harsher sanctions against the Islamic Republic.
Amano stressed the need for Iran to engage in serious talks to clarify issues in his report and said he wanted to send a high-level mission to the country to tackle increasing concerns about the nature of its nuclear activities.
"It is clear that Iran has a case to answer," Amano told a news conference on the sidelines of the board meeting.
"We have to alert the world before nuclear proliferation actually takes place."
Iran says it is enriching uranium only for nuclear power plants, not weapons, dismissing the intelligence information in the IAEA report obtained mainly from Western states as fabricated, and accusing the IAEA of pro-Western bias.
Amano said agency experts had examined the information carefully and put together a "clear, coherent and consistent picture" about Iran's activities.
He said he had written to the head of Iran's Atomic Energy Organisation, Fereydoun Abbasi-Davani, this month to suggest the visit, which would air issues raised by the IAEA report.
Amano said he hoped a "suitable date" could be agreed soon for his team's visit to Iran, which permits IAEA inspections of declared nuclear sites but since 2008 has stonewalled an agency investigation into "alleged studies" applicable to atom bombs.
"Throughout the past three years, we have obtained additional information which gives us a fuller picture of Iran's nuclear programme and increases our concerns about possible military dimensions," Amano told the board.
"The information indicates that Iran has carried out activities relevant to the development of a nuclear explosive device," he said, in his bluntest public statement so far on Iran's contested nuclear programme.
Diplomats described the powers' draft as a compromise text between Western states, which would have preferred tougher language, and Russia and China, which resisted.
It expressed "deep and increasing concern" about Iran's nuclear programme and called on it to open up fully to U.N. inspectors, according to a draft seen by Reuters.
The text urged Iran "to engage seriously and without preconditions in talks" to address nuclear concerns and asked Amano to report back to the board's next meeting in March.
It stopped short of actions with teeth such as reporting Iran once again to the Security Council, which has imposed four rounds of sanctions on the major oil producer since 2006. Russia and China oppose any more extensive measures.
But the fact that the six big powers ironed out an IAEA resolution will be welcomed in the West after Amano's report prompted Russia to complain that it was politicised and dimmed chances of a negotiated solution to the Iran nuclear dispute.
In contrast, Western states seized on the document to try to step up pressure on Tehran in the form of farther-reaching economic sanctions, which Russia and China oppose.
"It does the job," one senior Western diplomat said about the resolution. "It is always a compromise, but we want it to have the backing of as many of the board members as possible. That is the aim."
In November 2009, IAEA governors including Russia and China rebuked Iran for building a uranium enrichment plant in secret. Iran rejected that vote as "intimidation".
There has been concern that if the powers cannot settle their differences over how to nudge Iran into serious nuclear negotiations, then Israel, which feels endangered by Iranian nuclear aspirations, will attack it.
Israel is widely believed to have the Middle East's only nuclear arsenal to deter numerically superior enemies, but has never confirmed or denied it.
Russia has significant trade ties with Iran and also built its first nuclear power plant, launched at Bushehr earlier this year. China is a major importer of Iranian oil.
Editing by Richard Balmforth