The head of the UN's atomic watchdog has urged Iran to cooperate with a team of inspectors heading to Tehran, after a recent damning report on the Iranian nuclear programme.
International Atomic Energy Agency chief Yukiya Amano told AFP that the organisation's previous efforts to check Iran's claim its nuclear programme has only peaceful purposes had been hampered by "a lack of cooperation".
"We hope they will take a constructive approach. We hope that there will be substantial cooperation," Amano said on Friday.
An IAEA report in November highlighted a range of areas which had raised suspicions that Iran was pursuing the development of nuclear weapons, despite its repeated denials.
It detailed 12 suspicious areas such as testing explosives in a steel container at a military base and studies on Shahab-3 ballistic missile warheads.
Amano said it was too early to say definitively that Iran was pursuing a nuclear weapons programme.
But he added: "We have information that indicates that Iran has engaged in activities relevant to the development of a nuclear explosive device."
"We are requesting that Iran clarifies the situation. We proposed to make a mission and they agreed to accept the mission.
"The preparations have gone well but we need to see what actually happens when the mission arrives."
UN chief Ban Ki-moon said the onus was on Tehran to prove its good intentions to the inspectors, who will be visiting Iran from Sunday to Tuesday.
"There is no other alternative to addressing this crisis than peaceful resolution through dialogue," Ban told reporters in Davos.
Iran's President Mahmoud Ahmadinejad has insisted that Tehran is not dodging negotiations and was ready to sit down with world powers Britain, China, France, Russia, the United States, and Germany for talks.
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The six powers are waiting for Tehran to reply to an October letter sent by EU foreign policy chief Catherine Ashton that stresses that discussions should focus on the "key question" of the Iranian nuclear issue.
Previous talks held a year ago in Istanbul ended without progress.
"Iran should comply with the relevant Security Council resolutions. They have to prove themselves, that their nuclear development programme is genuinely for peaceful purposes which they have not done yet," Ban said.
Also in Davos, US Treasury Secretary Timothy Geithner said that more major countries, perhaps including China, were coming round to the idea of sanctions.
"China wants to be part of that effort. We're still at the early stage of the next wave of intensified financial pressure on oil and the financial side ... Europe has been excellent on this," he said.
"We are all engaged, it's an international effort ... trying ... to deter them from their nuclear ambitions. That's the most important thing."
China is a major importer of Iranian oil and has so far been reluctant to impose sanctions.
Ehud Barak, the defence minister of Iran's arch foe Israel, said that he did not expect Tehran to suddenly come clean about its nuclear programme.
"We have a high trust in the IAEA, especially under Amano," Barak told AFP in Davos, praising the November report.
"But I have no illusions about the Iranian regime... Iran has been defying and deceiving the whole world to get a nuclear capability."
Israel has been at the forefront of the drive to prevent Iran from acquiring nuclear arms, especially after Ahmadinejad called for the Jewish state to be wiped off the map.
Although it has never formally declared that it has atomic weapons, Israel is widely understood to be the only nuclear power in the Middle East.