Singapore raised its security alert and bolstered its defenses Friday after receiving information of a terrorist plot to attack vessels off the coast of the city-state in one of the world's busiest shipping lanes, a Cabinet minister said. Malaysia and Indonesia have also stepped up maritime and air patrols in the Malacca Strait, where millions of barrels of oil pass daily. Singapore's navy warned Thursday that a terrorist group was planning attacks on oil tankers and other vessels but provided no details. “All alert levels have been raised,” Home Affairs Minister Wong Kan Seng told Parliament, saying that the government has increased security at border crossings, airports, sea ports and at high-risk targets such as two new casino resorts. Wong did not say which terrorist group was planning the reported attack. “We received intelligence from our liaison partners about this possible plot to go and attack vessels coming through Singapore waters through the Malacca Strait,” Wong said. “As a result, the various security agencies have been working very closely with one another.” A Singapore-based terrorism expert said Al-Qaeda and the Southeast Asian militant group Jemaah Islamiyah - blamed for twin bombings last year on hotels in Jakarta - would be the most likely to carry out such an attack. “Certainly we know that in the past Al-Qaeda has had not only the intentions, but the capabilities to operate in the maritime environment,” said John Harrison, assistant professor at the S. Rajaratnam School of International Studies. Suspected JI operatives have been previously been arrested in Singapore. Also Friday, Indonesia's police chief Gen. Bambang Hendarso Danuri said authorities were investigating whether 14 suspected militants captured in a raid in Aceh province the previous day were linked to the threat. The raid came amid a police crackdown on militants in Aceh suspected of ties to Jemaah Islamiyah. Indonesia's president Susilo Bambang Yudhoyono said Friday the group had set up in the western province believing that Indonesian security forces had lost interest in Aceh since a violent separatist movement ended in 2005.