Tensions rose in the Middle East after two Saudi oil tankers were attacked near the Strait of Hormuz in the Persian Gulf, the world's most important oil transport route.

A fifth of global oil consumption passes through the choke-point strait from Middle East crude producers to major markets in Asia, Europe, North America and beyond.

The strait is 33km wide at its narrowest point, but the shipping lane is just 3km wide in either direction.

No one has claimed responsibility for the 6am attacks on Sunday, which came amid an escalating war of words between Iran and the United States over sanctions and the US military's presence in the region.

The US has deployed an aircraft carrier, bomber planes and defence missiles to the region amid rising tensions with Iran, which has threatened to block oil shipments through the strait if the US succeeds in halting its energy exports.

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