Russia will honour a contract to deliver advanced air defence missiles to Iran, Deputy Foreign Minister Sergei Riabkov said Friday.

"There is a contract on the delivery of these systems to Iran and we will honour it," the Interfax news agency quoted him as saying.

He said the "delay" in the delivery was "linked to technical problems."

Russian officials Wednesday announced a delay in the controversial contract to sell S-300 missiles to Iran, a day after Israeli Prime Minister Benjamin Netanyahu visited Moscow in a bid to add new pressure on Tehran.

"The delay is due to technical problems. The delivery will be carried out when they are resolved," Alexander Fomin, deputy head of Russia's Federal Service for Military-Technical Cooperation, told Interfax news agency.

Fomin, whose service oversees Russian arms exports, made the comments while attending a defence exhibition in New Delhi. He did not clarify what the problems were or how long it would take to fix them.

The engineer in charge of building the S-300s said there were nothing wrong with the missiles and called the delay a political decision.

"There are no technical problems with the S-300 systems. This is a political issue," Vladimir Kasparyants, head constructor of air defence systems at Almaz-Antey, the company that builds the S-300, told Interfax.

Russia's S-300 contract with Iran has raised hackles in the United States and Israel, which believe that Tehran could use the missiles to defend its nuclear facilities against attack.

Western powers suspect that Iran is seeking to build an atomic bomb under the guise of its civilian nuclear energy programme, although Tehran insists its nuclear project is peaceful in nature.

Neither the United States nor Israel have ruled out air strikes to stop Iran from acquiring nuclear weapons. Analysts say that S-300s could greatly complicate such air strikes.