The depth in certain stretches of the narrow Malacca Straits, one of the world's busiest shipping lanes, has changed slightly following the huge earthquake and killer waves which struck off Indonesia last month, according to the Malaysian navy.

But the busy strait is safe for navigation as the changes were "insignificant", Assistant Chief of Staff (plans and operations) Kamarulzaman Ahmad Badaruddin told Monday's edition of The Star.

"In certain areas, the change is just 0.2 meters while in the deep areas where the depth is about 100m, the difference is between one to two meters," he said.

"A ship normally has a draft of six meters and there is normally 30m below the draft. So there is no possibility that a ship will run aground," he added.

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.

Strategic 'choke point'

Kamarulzaman said the findings were based on surveys by the navy's hydrographic team in two separate locations - the northern channel approaching Malaysia's Penang port and the strategic "choke point " off One Fathom Bank - following the Dec 26 tsunami disaster.

"Even though the initial results did highlight changes in depth in some areas, the difference is (too) insignificant to cause any concerns. Positions of navigational aids such as buoys and underwater wrecks within the surveyed areas have not changed," he said.

The 9.0 magnitude earthquake off Sumatra's northwestern coast on Dec 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 20m, US geophysicists said.

The quake released huge tsunamis which devastated several Indian Ocean coastlines and are estimated to have killed more than 286,000 people. The Sumatra island province of Aceh was the hardest hit area.

The strait, 800km long and between 50km and 320km wide, has long been the haunt of pirates but the tsunamis had put an end, at least temporarily, to pirate attacks.