Iran kept tensions simmering over its threat to close the Strait of Hormuz to oil tankers by readying war game missile tests near the entrance to the Gulf yesterday.

Washington has warned a closure of the strait "will not be tolerated" after Iranian Vice President Reza Rahimi's threat this week that "not a drop of oil" will pass through the channel if more Western sanctions are imposed over Tehran's nuclear programme.

Iran has brushed off the warning from the United States, which bases its Fifth Fleet in the Gulf, with Iranian navy chief Admiral Habibollah Sayari saying it would be "really easy" to close the strait.

A spokesman for the Iranian navy, Commodore Mahmoud Mousavi, told state television yesterday that, "in the next days, we will test-fire all kinds of surface-to-sea, sea-to-sea and surface-to-air as well as shoulder-launched missiles" in the final stages of the war games.

The navy exercises started December 24 and are due to end tomorrow.

Twenty percent of the world's oil moves through the Strait of Hormuz, at the entrance of the Gulf, making it the "most important chokepoint" globally, according to information released Friday by the US Energy InformationAdministration.

Around 14 crude oil tankers per day pass through the narrow strait, carrying a total 17 million barrels. In all, 35 percent of all seaborne oil transited through there this year.