Indonesian Muslim groups, including one radical faction, will help police protect Christians attending Christmas Eve services to prevent a repeat of last year's wave of deadly church bombings.
A Jakarta police spokesman says various organisations will help 9,000 police personnel provide security at 650 churches and other places in the capital.
The groups include the radical "Front for the Defenders of Islam" which have been known to raid discos and bars, accusing them of encouraging anti-islamic behaviour.
Police say at least 100 members of the anti-bomb squad are on standby.
Last Christmas, several bombs exploded at churches in nine cities while Christians were holding masses, killing 14 people and injured scores of others.