Former prime minister and Nobel Peace Prize winner Jose Ramos-Horta has been sworn in as East Timor's new president.
Mr Ramos-Horta appealed for unity and an end to violence
Taking the oath of office in the capital, Dili, Mr Ramos-Horta vowed to work for unity and stability, urging an end to violence in the young nation.
But hours later there were clashes in Dili in which one man was killed.
The new president replaces Xanana Gusmao, who is to contest polls next month for the more powerful role of PM that Mr Ramos-Horta recently vacated.
Mr Ramos-Horta won the 9 May presidential run-off election with almost 70% of the vote, beating parliament head Francisco Guterres.
Many in East Timor hope his victory in relatively peaceful polls will bring stability to a nation struggling with severe poverty and still recovering from last year's violent clashes.
Several people were wounded in the clashes following Sunday's ceremony, as fighting broke out between supporters of rival political groups.
UN peacekeepers were deployed to restore order.
'End the crisis'
The swearing-in ceremony at parliament house coincided with the fifth anniversary of East Timor's formal independence.
Founder of East Timor's independence movement
Spent 24 years in exile after Indonesia invaded
Won Nobel Peace Prize in 1996
Former journalist, fluent in five languages
East Timor broke away from 25 years of Indonesian rule in a 1999 referendum, before being run under UN protection until May 2002.
Speaking after he was sworn in, Mr Ramos-Horta promised to find "the way to end the crisis of the country", and to tackle differences between the police and armed forces.
In May and June 2006 tensions between the two sides triggered weeks of street clashes that left more than 30 people dead and tens of thousands homeless.
Mr Ramos-Horta also appealed to young people to end a culture of clashes between street gangs.
"With vengeance and violence, we will not win over anything," he said. "With conscience in our hearts and our minds, with books and computers, we can win."
Mr Ramos-Horta has previously served as foreign minister. He spent years in exile leading the country's campaign for independence from Indonesia, for which he was awarded the Nobel Peace Prize in 1996.