Iran test-fired missiles yesterday to show it was prepared to head off any military threat, four days before the Islamic Republic is due to hold rare talks with world powers worried about its nuclear ambitions.

The missile manoeuvres coincide with escalating tension in Iran's nuclear row with the West, after last week's disclosure by Tehran that it is building a second uranium enrichment plant.

News of the nuclear facility south of Tehran added a sense of urgency to a crucial meeting in Geneva on Thursday between Iranian officials and representatives of six major powers, including the US.

Iran will be put "to the test" in Geneva and a move to sanctions would follow if the talks failed, US Secretary of State Hillary Clinton told CBS.

An Iranian official warned "fabricated Western clamour" over the new plant would negatively affect the talks at which the six powers want Iran to agree to open its facilities to inspection to prove its programme is for power and not nuclear weapons.

Ali Asghar Soltanieh, Iran's envoy to the UN's nuclear watchdog, said, referring to Western condemnation of the plant: "This ... approach will have a negative impact on Iran's negotiations with the 5+1 countries."

He has said Iran is arranging International Atomic Energy Agency inspections of the plant "in the very near future".

US President Barack Obama said on Saturday the discovery of the secret nuclear plant in Iran showed a "disturbing pattern" of evasion by Tehran.