There is no information of any imminent threat

Home Affairs Ministry statement

The Home Affairs Ministry said information on bomb building, photos and videos of targeted buildings, and al-Qaeda linked materials had been found in the suspects' homes and offices.

A government statement said the suspects had links to militant groups in Malaysia and Indonesia.

The Defence Minister, Tony Tan, said Singapore was vulnerable to terrorism because of its close links with the United States.

The authorities have said 14 of the suspects are Singaporean and the other is Malaysian.

Malaysian links

Saturday's announcement of the arrests, which took place in December, came a day after Malaysia said it had detained 13 people believed to have links with three men accused of the 11 September attacks on the United States.

Ghurka troops are guarding potential targets

Investigators are looking into possible links between both groups of suspects.

Thirteen members of the group detained in Singapore are believed to belong to a clandestine organisation called Jemaah Islamiah.

The Malaysian suspects allegedly belong to the Malaysian Mujahideen Group (KMM). The authorities say the KMM's aims include toppling the Malaysian government and establishing a hard-line Islamic state comprising Malaysia, Indonesia and the southern Philippines.

Singapore has been a staunch supporter of the American-led war against terror and has tightened its own anti-terror laws in the wake of the 11 September attacks.

The 15 men were arrested under the Internal Security Act, which allows suspects to be held without trial.