Jakarta – The approach of Christmas heightens the risk of terrorist attacks in Indonesia, said chief security minister Susilo Bambang Yudhoyono yesterday.

He said troops and police would be on high alert during the run-up to the festive season, which includes a two-day holiday at the end of the Muslim fasting month, to prevent any repeat of attacks such as last year's Bali bombings that killed 202 people, most of them Western tourists. "Yes of course I have to say ... the threat of terrorism is still imminent in Indonesia and in South-east Asia," he told ambassadors, businessmen and journalists in response to questions after a luncheon speech.

"Don't underestimate the potential threat of terrorism to Indonesia, now and in the future. We have captured many documents in raids on militants and they are still planning for conducting another strike in the future. Christmas, New Year ... is becoming a vulnerable date if we are not maintaining our readiness, our alert and our anticipated measures to prevent acts of terrorism. As always, we have to improve our security measures on those days."

A series of church bombings on Christmas Eve in 2000 killed 19 people. Some of those responsible have since been arrested for involvement in other attacks.

Mr Yudhoyono said Indonesia had arrested 97 suspected members of the Muslim militant network Jemaah Islamiah. Jakarta blames it for the Bali blasts, and for the JW Marriott Hotel bomb that killed 12 people in August.

Several top members of the network remain at large and are dangerous, Mr Yudhoyono said. "We also realise there are still more militants. These radical groups, who possess explosive devices, have the potential and capability of making further acts of terror," he added.

His comments come ahead of a brief visit to Bali by United States President George W. Bush tomorrow. The US leader will discuss the war on terror with his Indonesian counterpart Megawati Sukarnoputri during his visit.