Tehran: Iran says its powerful Revolutionary Guard is starting naval exercises near the Strait of Hormuz, the critical Gulf oil tanker route that Tehran has threatened to close in retaliation for tougher Western sanctions.

Iranian state media said on Saturday that the warships will conduct a month of maneuvers.

Western navies, meanwhile, have boosted their presence in the Gulf led by the American aircraft carrier USS Abraham Lincoln.

Iran has made no attempts to disrupt shipping through the strait, the route for one-fifth the world's crude oil.

The US and allies have said they would respond to any blockade. The Iranian war games follow stern warnings by Iran's Supreme Leader, Ayatollah Ali Khamenei, about any possible US or Israeli attacks against Tehran's nuclear facilities.