"If the enemy attempts a ground operation on Iranian islands or anywhere else on our territory, or if it seeks to impose costs on Iran through naval manoeuvres in the Persian Gulf and the Sea of Oman, we will open other fronts as a 'surprise'," the official was quoted as saying by the Tasnim news agency.

"The Bab el-Mandeb Strait is among the most strategic straits in the world, and Iran has both the will and the capability to pose a fully credible threat against it," the official said.

The Bab el-Mandeb Strait, like the Strait of Hormuz off the coast of Iran, is a chokepoint for global shipping that lies between Yemen and Djibouti at its narrowest point.

Iran has close links to and arms the Houthi rebel group in Yemen which greatly reduced Red Sea traffic in October 2023 when they began attacking vessels in retaliation for Israel's bombardment of Gaza.

The group has been battered by air strikes since, but analysts say the rebels could move from their position on the sidelines of the current US-Iran war and take a more active role.

However, the Houthis are seen as less ideologically tethered to Iran and have long enjoyed more independence than other Tehran-backed militant groups in the Middle East.

US President Donald Trump is moving thousands of airborne troops and extra marines to the Gulf amid speculation that he might order a limited ground invasion to either seize Iranian oil assets in the Gulf or secure the Strait of Hormuz.

One possible target is Kharg Island, which handles almost all of Iran's crude exports.

Trump has called it a "little oil island that sits there, so totally unprotected".

Shipping through the Strait of Hormuz has slowed to a trickle because of the conflict, disrupting roughly 20 percent of global oil supplies.

Crude prices have spiked to around 100 dollars a barrel as a result of what the International Energy Agency has called "the largest supply disruption in the history of the global oil market".