FACTBOX: The Strait of Hormuz, Iran and the risk

(Reuters) - Iran’s Revolutionary Guards said Iran would impose controls on shipping in the vital Gulf oil route if attacked and warned of reprisals, a newspaper reported last week.

Speculation has mounted that Iran could be attacked over its disputed nuclear program after a report said Israel had practiced such a strike. The United States has said it wants a diplomatic end to the atomic row but has not ruled out force.

Analysts say Iran, OPEC’s second largest crude producer, could seek to impede Gulf shipping if pushed. U.S. naval chiefs are concerned Iran could resort to mining the Strait of Hormuz and the wider Gulf in a major conflict.

The sea channel which shares Iran’s coastline at the entrance to the Gulf is the world’s most important waterway because of the huge volume of oil exported through it daily.

Here are some facts about the Strait of Hormuz:

-- Oil flows through the Strait account for roughly 40 percent of all globally traded oil supply, according to the U.S. Energy Information Administration (EIA). The figure fluctuates with changing OPEC output.

-- In May 2007, the International Energy Agency (IEA) estimated 13.4 million barrels per day (bpd) of crude passed through the narrow channel on tankers.

-- An additional 2 million barrels of oil products, including fuel oil, are exported through the passage daily, as well as liquefied natural gas (LNG).

-- Exports from the world’s largest LNG exporter Qatar also pass through the Strait en route to Asia and Europe, totaling some 31 million tonnes a year.

-- Ninety percent of oil exported from Gulf producers is carried on oil tankers through the Strait.

-- One of U.S. Central Command’s (CENTCOM) key missions in the Gulf is to ensure the free flow of oil and energy supplies.

-- Between 1984 and 1987, a “Tanker War” took place between Iran and Iraq, where each nation fired on the other’s oil tankers bound for their respective ports. Foreign-flagged vessels were caught in the crossfire.

-- Shipping in the Gulf dropped by 25 percent because of the exchange, forcing the intervention of the United States to secure the shipping lanes.

-- Iran has admitted to deploying anti-aircraft and anti-ship missiles on Abu Musa, an island strategically located near the Strait’s shipping lanes.

-- The EIA predicts oil exports passing through the strait will double to between 30 million and 34 million bpd by 2020.

-- Over 75 percent of Japan’s oil passes through the Strait.

-- Merchant ships carrying grains, iron ore, sugar, perishables and containers full of finished goods also pass through the strategic sea corridor en route to Gulf countries and major ports like Dubai.

-- Heavy armor and military supplies for the U.S. armed forces in Iraq and other Gulf countries pass through the channel aboard U.S. Navy-owned, U.S.-flagged and foreign-flagged ships.

-- Geographic location: a narrow bend of water separating Oman and Iran connects biggest Gulf oil producers like Saudi Arabia with the Gulf of Oman and the Arabian Sea.

-- At its narrowest point, the Strait is only 34 miles across.

-- The Strait consists of 2-mile (3.2-km) wide navigable channels for inbound and outbound tanker traffic as well as a 2-mile wide buffer zone.

Sources: International Energy Agency (IEA), U.S. Energy Information Administration (EIA), United Nations Conference on Trade and Development (UNCTAD),, U.S. Navy’s Military Sealift Command, Clarkson shipping consultancy.

Reporting by Stefano Ambrogi