Violence has broken out in several areas of East Timor, a day after independence hero Xanana Gusmao was named as the new prime minister.
Protesters set fire to buildings in anger at Mr Gusmao's appointment
Protesters threw rocks and set fire to buildings, and security forces used tear gas in response.
Mr Gusmao was chosen as the new premier to end weeks of deadlock, after no single party won a majority in June's parliamentary elections.
But his party's main rival, Fretilin, denounced the decision as illegal.
About 100 youths from a predominantly pro-Fretilin refugee camp near the international airport threw rocks at police on Tuesday, according to a reporter for the French news agency AFP.
Police then fired tear gas towards the group, who were reportedly yelling "Fretilin! Fretilin!".
Other witnesses report seeing mobs setting fire to government buildings in the eastern districts of Baucau and Viqueque.
The unrest triggered fears of an end to the fragile peace that has held since mid-2006, when violent feuding between rival army and police units spilled out on to the streets.
More than 30 people were killed and thousands were forced to flee their homes in the 2006 unrest.
Risk to stability
June's election had been seen as a fresh start for the young, impoverished nation, but neither Fretilin nor the CNRT party led by Mr Gusmao - who was East Timor's president until May 2007 - were able to achieve an overall majority.
Weeks of wrangling ensued, but to little effect.
Former guerrilla leader who led East Timor to independence
Spent six years in Indonesian prison
Made first post-independence president
Stepped down in early 2007 to run for more hands-on role of PM
In the end, President Jose Ramos-Horta used his constitutional right to settle the matter - and he chose in favour of Mr Gusmao.
The BBC's Lucy Williamson, in Jakarta, says that although Mr Ramos-Horta's decision risked a violent reaction from Fretilin supporters, he may have decided that allowing the country to stagnate under a minority government would be an even bigger risk to stability.
But just hours after Mr Ramos-Horta had made his decision, the head of the Fretilin party, ex-prime minister Mari Alkatiri, was quick to voice his anger.
"We regard it as a political and illegal decision," he said. "That is why, the government... will never have the co-operation of Fretilin - because this is an illegal government."
But Mr Ramos-Horta urged Fretilin supporters not to turn to violence.
"Do not think that Fretilin has lost. Fretilin is a very important party at the parliament which will become the best opposition because it has experience and the capacity for that," he told reporters.
"I appeal to youths and the public to be calm and give the chance to Brother Xanana to govern," he added.