Iran has begun a series of military exercises aimed at preparation against attacks on its nuclear facilities.

Military officials in Iran have said the exercises are to try out new weapons systems and test whether its communications links can withstand electronic warfare.

The exercises have coincided with increasing tensions over a deal that was meant to ease western concerns about Iran pursuing nuclear weapons.

Iranian officials have raised objections to an offer by the International Atomic Energy Agency to enrich Iran's uranium abroad.

While the United States and Israel have not ruled out a military option should negotiations over Tehran's nuclear program fail, military officials in Iran have said even if Israeli warplanes manage to get through Iranian defences, Iran will launch surface-to-surface missiles to destroy Israeli air force bases.

The five days of air defence drills will cover than half a million square kilometres in Iran.