Iran says it will fire long-range missiles on Saturday as part of military exercises in the Gulf.

The announcement on Friday was made on the heels of heightened tensions between Iran and Western powers over Tehran's threat to block oil shipments through the strategic Strait of Hormuz.

The semi-official Fars News agency quotes an Iranian admiral as saying the navy will test several kinds of missiles, including long-range ones, as part of a military drill that began on December 24. He says the test firings are the final phase of the drill to “prepare the navy for confronting the enemy” in any war situations.

Iran's arsenal incudes the Shahab-3 missile, which could reach Israel and some U.S. bases in the Middle East.

Earlier this week, Tehran threatened to block the entrance to the Persian Gulf if Western powers imposed sanctions targeting its oil exports.

Such a move would add to several rounds of sanctions already imposed on Iran over its controversial nuclear program.

More than one-third of the world's tanker-borne oil supply passes through the Strait of Hormuz. A closure could temporarily cut off some oil supplies and impact the price of oil worldwide.

The Pentagon said interfering with the passage of vessels through the strait will not be tolerated.

Separately, the Associated Press quoted a Saudi oil ministry official as saying Gulf oil producers would be ready to step in, if necessary, to make up for any losses.