The United States warned Iran on Wednesday that any move to block shipping in the Strait of Hormuz, the world's most important oil transit channel, will not be tolerated.

The warning came after Iran's navy chief Admiral Habibollah Sayari said in an interview that "shutting the strait for Iran's armed forces is really easy -- or as we say (in Iran) easier than drinking a glass of water."

"But today, we don't need (to shut) the strait because we have the Sea of Oman under control, and can control the transit," he told Iran's Press TV.

Washington responded with a strong warning against any attempt to disrupt shipping at the entrance to the Gulf, through which more than a third of the world's tanker-borne oil passes.

"Interference with the transit ... of vessels through the Strait of Hormuz will not be tolerated," Pentagon press secretary George Little said on Wednesday.

The strait is a strategic choke point linking the Gulf's petroleum-exporting states of Bahrain, Iran, Kuwait, Qatar, Saudi Arabia and the United Arab Emirates to the Indian Ocean.

The United States maintains a naval presence in the Gulf in large part to ensure that passage for oil remains free, and the US Fifth Fleet is based in Bahrain.

Admiral Sayari was speaking a day after Vice President Mohammad Reza Rahimi threatened to close the strait if the West imposed more sanctions on Iran, and as its navy held war games in international waters to the east of the channel.

World prices briefly climbed after Rahimi warned on Tuesday that "not a drop of oil will pass through the Strait of Hormuz" if the West broadened sanctions against Iran over its nuclear programme.

"The enemies will only drop their plots when we put them back in their place," the official news agency IRNA quoted Rahimi as saying.

Sayari asserted that the Strait of Hormuz "is completely under the control of the Islamic Republic of Iran."

He said Iran's navy was constituted with the aim of being able to close the strait if necessary.

"The Iranians conduct exercises on a fairly routine basis in this area. That's something that we know about," Little said in Washington.

"That being said, any effort to raise the temperature on tensions surrounding the Strait of Hormuz is unhelpful," he said, adding that there was no sign of Iran taking provocative steps near the channel.

"I'm unaware of any aggressive hostile action directed toward US vessels in the Persian Gulf or the Strait of Hormuz," or against other ships, Little said.

As Iran staged its military manoeuvres, an American aircraft carrier, the USS John Stennis, and a guided-missile cruiser, the USS Mobile Bay, moved through the Strait of Hormuz.

Little said this was "a pre-planned, routine transit" on the way to the Arabian Sea to provide air power for the war in Afghanistan.

France on Wednesday called on Tehran to respect international law and allow unhindered passage of all vessels through the strait.

Sayari, meanwhile, said the Islamic republic's naval manoeuvres were designed to show Gulf neighbours the power of its military over the zone.

Iranian ships and aircraft dropped mines in the sea on Tuesday as part of the drill, and on Wednesday drones flew out over the Indian Ocean, according to a navy spokesman, Admiral Mahmoud Mousavi.

Iran has said several times it is ready to target the strait if it is attacked or economically strangled by Western sanctions over its nuclear programme.

An Iranian lawmaker's comments last week that the navy exercises would block the Strait of Hormuz briefly sent oil prices soaring before that was denied by the government.

Tehran in September rejected a Washington call for a military hotline between the capitals to defuse any "miscalculations" that could occur between their navies in Gulf waters.

US State Department deputy spokesman Mark Toner had dismissed Rahimi's threat as another attempt "to distract attention from the real issue, which is their continued non-compliance with their international nuclear obligations."

The United States and other Western countries accuse Iran of using its uranium enrichment programme to build nuclear weapons. Tehran denies the charge.

Extra US and European sanctions aimed at Iran's oil and financial sectors are being considered.

A European Union spokesman said on Wednesday the bloc was pressing ahead with those plans regardless of Tehran's threat.

The Strait of Hormuz: key route for world's oil
Dubai (AFP) Dec 28, 2011 - The Strait of Hormuz, which Iran has threatened to block if the West applies sanctions on its oil exports, is a strategically important waterway through which 40 percent of the world's oil transits.

The strait links the Gulf, bordered by petroleum-rich states like Bahrain, Kuwait, Qatar, Saudi Arabia and the United Arab Emirates, with Oman.

Iran's Vice President Mohammad Reza Rahimi warned Tuesday: "If sanctions are adopted against Iranian oil, not a drop of oil will pass through the Strait of Hormuz."

Several Western states are considering oil sanctions against Iran over its nuclear programme, accusing it of seeking to develop nuclear weapons.

The narrow Strait of Hormuz has a maximum width of some 50 kilometres (30 miles) and a maximum depth of 60 metres (200 feet).

The corridor is dotted with little-inhabited desert islands, which are nevertheless strategically important, notably the Iranian islands of Hormuz and Qeshm and Hengam off Bandar Abbas.

Oman's Musandam Peninsula juts out to the Strait of Hormuz towards Iran, separated from the rest of the sultanate by land belonging to the UAE.

With their back to the UAE coast, the three strategic and disputed islands of Greater Tunb, Lesser Tunb and Abu Musa serve as observation posts on all Gulf States: the UAE, Qatar, Bahrain, Saudi Arabia, Kuwait, Iraq and Iran.

Iran under the Western-backed shah gained control of the islands in 1971, as Britain granted independence to its Gulf protectorates and withdrew its forces.

Abu Musa, the only inhabited island of the three, was placed under joint administration in a deal with Sharjah, now part of the UAE.

But the UAE says the Iranians have since taken control of all access to the strategic island and installed an airport and military base there.

Iran's Revolutionary Guard, the ideological army of the Iranian regime, controls naval operations in the Gulf and the Strait of Hormuz.

In the event of war, the Islamic republic could block access to the oil-rich region, according to a US intelligence report published in late 2009.

More than a third of the world's tanker-borne oil passes through the Strait of Hormuz.

The United States maintains a navy presence in the Gulf in large part to ensure that passage remains free.

Iran is carrying out navy exercises in international waters to the east of the Strait of Hormuz.