In 2007 the UN stepped up sanctions over Iran's nuclear programme by banning its arms exports [Gallo/Getty]

Nigeria has reported the seizure of an arms shipment from Iran that was intercepted by its secret service in Lagos to the United Nations Security Council, Nigeria’s foreign minister has said.

As a UN member, Nigeria was obliged to report the seizure of rockets and other explosive found hidden on a ship from Iran last month.

"Following preliminary investigations, our permanent mission in New York has reported the seizure and inspection of the arms shipment from Iran in compliance with our reporting obligations under [UN] resolution 1929," Odein Ajumogobia said on Monday.

The final destination for the arms is unclear and it is possible that the busy port of Lagos, where the weapons were seized, could have been a transit point before the shipment was to travel to a final destination.

The Nigerian secret services said on Wednesday that it had already been monitoring the movement of the cargo before it entered the port in July.

Nigerian investigations have focused on two Iranians suspected to be members of the al-Quds, an elite unit of the Revolutionary Guards that specialises in foreign operations on behalf of Iran, according to diplomatic sources.

The country's secret service questioned one of the men, who had taken refuge in the Iranian embassy in Abuja, the Nigerian capital. It was unable to question the second suspect, who has diplomatic immunity.

Manouchehr Mottaki, the Iranian foreign minister, said on Monday that the "misunderstanding" over the seized weapons had been resolved.

"The seized cargo belonged to a private company and it was for sale legitimately to a West African country," Mottaki said in Tehran, without identifying the country.

"One of the Iranian citizens ... provided all the necessary explanations to Nigerian officials," he said.

Breach of sanctions

Diplomats say the arms shipment could put Iran in breach of UN sanctions imposed over its refusal to halt its nuclear programme.

In a 2007 resolution stepping up sanctions on Iran over its nuclear programme, the UN Security Council banned Iranian arms exports, forbidding the sale or supply of weapons by Iran, whether directly or indirectly.

The resolution states that Iran must not "supply, sell or transfer directly or indirectly from its territory or by its nationals ... any arms or related material".

It also requires nations to prevent any such transfers and prevent their citizens from obtaining any weapons from Iran.

An international shipping company based in France has said one of its ships picked up the containers from Bandar Abbas, a port in southern Iran.

The company, CMA CGM, said that it was the victim of a false cargo declaration. It has said it is co-operating fully with investigating agencies.

The cargo was labelled as building materials and was transferred to a warehouse in Lagos.

The consignee was a Nigerian, also under investigation, and the goods were originally meant for an address in Abuja, Ajumogobia said. But they were intercepted when they were returned to the port in an attempt to re-export them.

"At that point another set of shipping documents appeared and the individuals who were connected to the shipment suggested these goods were being trans-shipped through Nigeria to a third country, the Gambia," Ajumogobia said.

"That aspect of the investigation has not been concluded."