"We are warning the free world to beware of Iran's plans... We are closely monitoring these worrying projects being plotted in Iran," said one senior official.

"Iran is trying to develop a nuclear weapon and is developing its vectors to this end. Its ballistic missiles do not only threaten Israel: they can also be turned on Europe," he told AFP.

The international community, particularly Israel, has sounded repeated alarms over Iran's nuclear activities, despite EU-led efforts to resolve the matter without recourse to the UN Security Council and possible sanctions.

Iran announced earlier it had successfully tested a new solid fuel missile motor for its arsenal of medium-range ballistic missiles, a breakthrough likely to cause fresh international concern.

Iran insists it is not seeking to develop nuclear weapons or missiles with a longer range. Tehran says its missiles will only be tipped with conventional warheads.

Israel itself has never admitted to having atomic weapons, but is thought to have around 200 nuclear warheads. It publicly opposes any build-up of nuclear weapons in the Middle East, saying it could distort the region's balance of power.