Jakarta police have said they would boost security in the capital ahead of Christmas to avoid a repeat of 2000 Christmas Eve bombings on churches in several Indonesian cities, including in the country's capital.

A youth wing affiliated with Indonesia's largest Muslim group Nahdlatul Ulama, some 40 million strong, said that members would guard churches for the coming Christmas festivities and it had persuaded youths from other religions to join the project.

"We have an annual programme to set up posts to secure Christmas. For this year, I have contacted groups from other religions like the Hindus and Buddhists and they have responded positively," said Tatang Hidayat, National Coordinator of NU's Banser group, known for its military-like uniform.

Hidayat said the volunteers would closely collaborate with existing police operations and the churches' own security.

Around 17,000 policemen are expected to safeguard Christmas celebrations in Jakarta alone.

The spate of bombings in 2000 killed at least 19 people, including a Banser member guarding a church in East Java.

The attacks along with other blasts in recent years -- most recently on the tourist island of Bali in October when suicide bombers killed 20 people -- have been blamed on Jemaah Islamiah, a militant network intelligence experts call a Southeast Asian wing of al-Qaeda.

Around 85 per cent of Indonesia's 220 million people are Muslim. Christians form the second largest religious group in the country as a whole, as well as in Jakarta.

Although Indonesia has been relatively calm in recent weeks, many security analysts say threats of militant attacks still run high because police have yet to catch one of the alleged masterminds of previous bombings, Malaysian-born Noordin M. Top.

Police last month killed Azahari Husin, another alleged Jemaah Islamiah leader, in a shootout in East Java province.