Reuters/Vienna

The UN nuclear watchdog said yesterday little substantive headway has been made so far in its long-running investigation into suspected bomb research by Iran, a setback to hopes for an end to a standoff over its atomic activity.

The lack of movement in the inquiry by the International Atomic Energy Agency will disappoint the West and could further complicate efforts by six world powers to negotiate a resolution to a decade-old dispute with Iran over its nuclear ambitions.

An IAEA report said Iran had failed to address key questions about alleged research that could be used to develop nuclear weapons by an agreed August 25 deadline.

The Islamic Republic had implemented just three of five nuclear transparency steps by last month’s target date under a confidence-building deal it reached with the Vienna-based IAEA in November, according to the quarterly report.

It said Iran, where a moderate president took office a year ago and revived nuclear diplomacy with the West, had told the IAEA that most suspicions about the nature of its programme were “mere allegations and do not merit consideration”.

The IAEA had also observed via satellite imagery “ongoing construction activity” at Iran’s Parchin military base, the report said. Western officials believe Iran once conducted explosive tests there of relevance in developing a nuclear weapon and has sought to “cleanse” it of evidence since then. Iran has long denied UN nuclear inspectors access to the base.

In what big powers are likely to see as a positive note in the report, Iran cut its stockpile of low-enriched uranium - potential bomb fuel - to 7,765kg in August from 8,475kg in May. Iran struck an interim deal with the powers last November to scale back some sensitive aspects of its nuclear advances.

Iran dismisses suspicions that it seeks to develop nuclear weapons capability from its enrichment of uranium. It says the programme is for peaceful energy purposes only.

While rejecting the allegations, Iran has been promising to co-operate with the IAEA since Hassan Rohani, widely seen as a pragmatist, was elected president in 2013.

As part of the co-operation agreement reached between the IAEA and Iran late last year to try and revive the stalled investigation, Tehran agreed in May to carry out five specific steps by late August to help allay international concerns.

It promised to provide information on two issues that are part of the IAEA’s inquiry into the possible military dimensions of the country’s nuclear programme: alleged experiments on explosives that could be used for an atomic device, and studies related to calculating nuclear explosive yields.

The IAEA report said discussions had begun on these two issues at an August 31 meeting in Tehran, but gave no details.

Western officials say Iran must address the IAEA’s concerns if there is to be any chance of success in the parallel diplomatic negotiations aimed at curbing the country’s nuclear work in exchange for a gradual ending of sanctions on Tehran.

Iran and the United States, France, Germany, Britain, Russia and China failed to meet a July target date for reaching a comprehensive deal because of persistent wide differences over the permissible size of Iran’s uranium enrichment programme.

They now face a new deadline of November 24, with talks between the seven states due to resume in New York later this month.

Rohani’s election in mid-2013 raised hopes of a settlement of the dispute after years of tension and fears of a new Middle East war, and an interim accord was reached between Iran and the six powers in Geneva late last year.

But Western diplomats say the sides remain far apart on what a final deal should look like - especially on the issue of how many enrichment centrifuges Iran can operate - and that a successful outcome in the negotiations is far from guaranteed.

While the big powers’ diplomacy is focused on limiting Iran’s future production of enriched uranium, the IAEA has for years been investigating alleged research in the past that could be used to turn such fissile material into atomic bombs.