An Iranian lawmaker warned on October 2 that any American attack on Iran would open "new fronts" and provoke a missile response that would "surprise the world."

Ruhollah Mousavi, a member of parliament's internal affairs committee, made the remarks as the US announced the deployment of about 9,000 additional troops to the Middle East.

"If America attacks Iran, Tehran will respond with missiles that will surprise the world," Mousavi said, adding that a strike would expand the conflict rather than contain it.

The warning is the latest in a week of escalating rhetoric between the two countries. The US is moving the USS Theodore Roosevelt carrier strike group and the USS Makin Island amphibious ready group toward the region.

Tehran has consistently said its missile programme is defensive. But Iranian officials have stepped up their warnings as American forces gather in the Gulf.

Analysts say both sides are trying to shape the other's calculations before any confrontation. The US insists its build-up is meant to deter aggression, while Iran says it will answer any attack.

Oil prices have climbed above $102 a barrel this week as markets price in the risk of supply disruptions through the Strait of Hormuz.