* Protest began after bodies of Dinka tribesmen found
* Civilians seek refuge at U.N. compound in Wau
JUBA, Dec 20 (Reuters) - Hundreds of civilians have sought refuge at a U.N. mission in South Sudan to flee shooting and clashes between police and armed youth, the United Nations and residents said on Thursday.
South Sudan won independence from Sudan last year but the government has been struggling to assert control over a country the size of France that is awash with arms after decades of civil war with the north.
Last week, South Sudan's army shot dead at least nine people in the northern city of Wau who were protesting against the relocating of a local council headquarters, according to the United Nations.
On Wednesday, new clashes broke out between police and residents, witnesses said. Details were unclear but residents said the protest started after six bodies of Dinka tribespeople had been found.
Witnesses said armed Dinka youth set ablaze several buildings in Wau, the capital of Western Bahr El Ghazal state. Police used teargas to disperse the protest, while shooting could be heard, residents said.
"Some youths ... began the shooting. Police intervened and began exchanging fire with them," a witness said.
Kouider Zerrouk, spokesman for the U.N. Mission in South Sudan, said hundreds of civilians, mainly women and children, had sought refuge at the U.N. compound in Wau.
"They are under the protection of the mission," he said.
James Deng Dimo, a journalist in Wau, said hundreds of police officers were patrolling the streets on Thursday after reinforcements arrived from the capital Juba by plane. Many residents were leaving the town.
"They are going to the rural areas because they fear there might be a repeat. Where I am standing I can see people carrying luggage like mattresses, beds and bags," he said.
There was no immediate comment from authorities but the government was planning to hold a news conference later in the day.
Human rights groups regularly accuse the army and police, a collection of former guerillas, of human rights abuses.
South Sudan is in the middle of a severe economic crisis after shutting down its oil production, which contributed to 98 percent of state income, in January in a row with Sudan over export fees.
About 2 million people died in Sudan's north-south civil war over ethnicity, religion, oil and ideology. (Reporting by Charlton Doki and Ulf Laessing; Editing by Michael Roddy)