The UN atomic energy watchdog, the International Atomic Energy Agency (IAEA) is expected to detail the reasons behind its growing concern that Iran may be developing a nuclear missile.

The IAEA could detail the reasons for its concern in a new report on Iran in November. The report is expected to increase international pressure on Tehran.

The US and its allies have urged IAEA Director General Yukiya Amano to say whether there have been military aspects to Tehran’s nuclear activities.

Iran maintains it is enriching uranium solely for peaceful electricity generation.

In separate news, Iran’s Foreign Ministry says Russia’s decision to scrap its planned $800m arms deal with Tehran will not affect diplomatic relations between the two countries.

“Matters of this kind must not have any negative effect on political relations, nor are they having any such effect,” says Foreign Ministry spokesman Ramin Mehmanparast.

“However, we still cannot understand the reason for the non-delivery of what are considered to be defensive systems.”

Iran is now seeking compensation from Russia in international arbitration for breach of the contract, which was signed in 2007. The contract stated that Moscow would supply five battalions of S-300 advanced air-defence missile systems to Tehran.

In September 2010, the Kremlin banned the sale saying the systems were covered by the fourth round of sanctions imposed against Iran by the UN Security Council.

So far, Russia has paid back Iran’s initial $166.8m payment.