Ships are seen off the coast of Singapore, Thursday March 4, 2010. Singapore's Navy is warning that a terrorist group is planning attacks on oil tankers in the Malacca Straits. According to an advisory issued Wednesday by the Navy's Information Fusion Center seen by The Associated Press, terrorists may also be targeting other vessels in the shipping lane off Malaysia's east coast. (AP Photo/Wong Maye-E)

Ships are seen off the coast of Singapore, Thursday March 4, 2010. Singapore's Navy is warning that a terrorist group is planning attacks on oil tankers in the Malacca Straits. According to an advisory issued Wednesday by the Navy's Information Fusion Center seen by The Associated Press, terrorists may also be targeting other vessels in the shipping lane off Malaysia's east coast. (AP Photo/Wong Maye-E)

A Police Coast Guard vessel patrols the shipping lanes near freight ships off the coast of Singapore March 4, 2010. REUTERS/Vivek Prakash


A Police Coast Guard vessel patrols the shipping lanes near freight ships off the coast of Singapore March 4, 2010. REUTERS/Vivek Prakash

Container ships and oil tankers are seen in the shipping lanes off the coast of Singapore March 5, 2010. Singapore said on Friday it had raised alert levels in the city-state and beefed up security at its airport and new casino resorts, after a warning by its navy of possible attacks on oil tankers in the region. REUTERS/Vivek Prakash
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An aerial photo shows a vessel (bottom) sailing past ships anchored along the coastal line off Singapore in 2008. Singapore has raised security alert levels following threats of possible terrorist attacks on ships in the busy Malacca Strait waterway, the country's interior minister said Friday. (AFP/File/Roslan Rahman)