Indonesia's chief security minister said the government was sending in extra troops to Borneo, worried that the ethnic bloodshed which has already killed up to 400 people there could spread.
Mr Susilo Bambang Yudhoyono that security in the worst hit town of Sampit had been restored.
"Sampit is under control now but there are indications that the problem may spread to more remote places which are difficult to reach. Because of that, we will deploy another additional battalion to strengthen the situation here," he said.
Indonesia has said it would also send in special forces to quell the unrest, which flared more than week ago when gangs of indigenous Dayaks began attacking Madurese immigrants.