Indonesia has closed its border with East Timor after rebels raided an East Timorese police post and seized a large number of automatic weapons.
PM Jose Ramos-Horta says there will be no dialogue with the rebels
This was done to prevent the rebels from escaping into Indonesian territory, officials in Jakarta said.
East Timor is preparing for elections in April after the previous government collapsed in May 2005.
The island nation won independence from Indonesia in 1999 following a UN-sponsored referendum.
UN forces in East Timor say the attack was carried out by a rebel group led by a renegade army officer.
A member of the border police told the Associated Press news agency that 23 weapons were stolen in the raid.
Subsequently, the country's Prime Minister Jose Ramos-Horta asked the Indonesian government to close its border with East Timor so that government and international forces could track down the rebels.
Maj Alfredo Reinaldo, leader of the rebel group, led a military revolt last May, which resulted in violence between rival security forces and the collapse of the government of then Prime Minister Mari Alkatiri.
Maj Reinaldo was later arrested by Australian troops, but then managed to escape from prison, AP said.
Until recently, the government was trying to negotiate with the ex-army officer in a bid to make him surrender.
But after the raid, Prime Minister Ramos-Horta said that there would be no more dialogue with Maj Reinaldo.
Observers fear this could escalate tensions in the country, whose short history has been marred by ethnic and political violence.
The international forces in East Timor have warned of further trouble in the run-up to presidential and parliamentary elections in April.