Indonesians observed Christmas peacefully across the country as tens of thousands of police and troops remained on high alert for possible terrorist attacks.

The security forces had earlier warned of possible terrorist attacks during the Christmas and New Year holidays as militants might seek revenge for the killing last month of Malaysian bomb-expert Azahari bin Husin, a senior member of the regional terror network Jamaah Islamiyah (JI), during a police raid in East Java.

JI has been blamed for a series of bomb attacks in the country, including the deadly and near simultaneous Christmas Eve church bombings in 2000.

But as of late Sunday the world's most populous Muslim nation remained peaceful, police said.

"Up until now, the security situation across the country remains safe and under control. We will continue to stay fully alert for future threats to security," national deputy police spokesman Anton Bahrul Alam told AFP.

Some 47,000 police and soldiers have been deployed to guard churches and Christian houses of worship, hotels, and shopping malls. Even security guards dressed as Santa Claus were seen checking vehicles for explosives at the Mandarin Oriental Hotel in Jakarta, AP reported.

President Susilo Bambang Yudhoyono attended a Christmas celebration in Nias, North Sumatra, on Sunday. Also present at the event was Timor Leste President Xanana Gusmao, who on Saturday evening attended a Christmas Eve mass at Jakarta's cathedral. Susilo and Gusmao are slated to attend an event to mark the first anniversary of the Dec. 26 tsunami in neighboring Aceh province.

Nias Island, which was also affected by last year's tsunami, was shaken by a 4.6-magnitude earthquake on Sunday morning just before the arrival of the President and other distinguished guests for the Christmas celebration.

During the celebration, which was held in a soccer field and drew a crowd of more than 6,000, Susilo said that his visit to the mainly Christian island was a display of his "empathy for the people of Nias and southern Nias who suffered so much because of the earthquake and the tsunami."

"With the spirit of Christmas, it is my hope that the people of Nias can bounce back and further rebuild Nias," he was quoted as saying by AFP.

Presidential spokesman Andi Mallarangeng told reporters earlier in the day that the presidential guard had increased security for the country's leading family following intelligence reports of "serious threats against the safety of the President and his family".

Meanwhile, Indonesian Christians living in a number of cities considered susceptible to terror attacks, such as Jakarta, Poso and Palu, marked Christmas Eve without any signs of fear despite the presence of security officers in their churches.

Bomb squad personnel and security officers scoured churches on Saturday before Christmas Eve services, and searched for suspicious items around foreign embassies and shopping malls.

In the Central Java capital of Semarang, thousands of Christians flocked to churches from Saturday morning to midnight amid good weather.

In a show of religious harmony, members of the Nahdlatul Ulama (NU) civilian guards, known as Banser, helped police officers to guard the houses of worship. The NU is the country's largest Muslim organization.

Ali Maffudz, who leads the province's NU civilian guards, said that as many as 3,500 Banser members had been deployed to support the security forces guard churches across Central Java.

In neighboring Yogyakarta, Christians celebrated their Javanese-style Christmas in peace.

Kendari, the capital of Southeast Sulawesi, continued its tradition of celebrating peaceful Christmases. There was no sign of security disturbances during the annual celebrations.

Police officers maintained low profile security measures to guard some 30 churches in the predominantly Muslim city