The narrow waterway, which separates peninsular Malaysia from the Indonesian island of Sumatra and links the Indian Ocean with the South China Sea, is used by some 50,000 ships a year carrying a third of world trade and half its oil supplies.

The navy's hydrographic survey team will spend several months re-charting the strait, with the depth along the designated shipping lane top priority, a Maritime Department official told the Malay Mail.

Meanwhile, ships have been asked to use their echo sounders as a precautionary measure while navigating the strait, particularly near the shallow One Fathom Bank, Malaysian Maritime Institute president Jaffar Lamri said.

The 9.0 magnitude earthquake off Sumatra's northwestern coast on December 26 was so powerful it made the Earth wobble on its axis and permanently altered the regional map, possibly shifting some small islands as much as 20 metrers (66 feet), US geophysicists said.

The quake released huge tsunamis which devastated several Indian Ocean coastlines, killing more than 168,000 people. The Sumatra island province of Aceh was the hardest hit area.

The strait, 800 kilometres (500 miles) long and between 50 and 320 kilometres wide, has long been the haunt of pirates. But Jaffar told AFP that the tsunamis had put an end, at least temporarily, to pirate attacks.

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