NEW YORK (AFP) - Aid agencies need US$166 million (S$210 million) over the next three months to help civilians in violence-wracked South Sudan, the United Nations said on Wednesday.

The money is needed for maintaining health and sanitation, distributing food, as well as managing camps for those displaced by the recent ethnic clashes, the Office for the Coordination of Humanitarian Affairs said in a statement.

It would also be used to help some 200,000 refugees from neighbouring Sudan who have fled to the South Sudanese states of Unity and Upper Nile.

"There are at least 90,000 people who have been displaced in the past ten days. This includes 58,000 people who are sheltering in UN peacekeeping bases," said UN humanitarian coordinator for South Sudan Toby Lanzer in the statement.

"This is an extremely difficult time for the people of this new nation, and it is crucial that aid agencies have the resources they need to save lives in the coming months," he added.

He expressed hope that donors would "act swiftly" to raise the necessary funds.

The United Nations says thousands have been killed in South Sudan since December 15 when violence erupted after President Salva Kiir accused his former vice president, Riek Machar, of attempting to overthrow him in a coup.

Machar denied it and accused Kiir of carrying out a vicious purge of his rivals.

The battle for power sparked violence between their two ethnic groups, with Nuers supporting Machar and Dinkas for Kiir.

On Tuesday, the UN Security Council voted to send an additional 6,000 peacekeepers in a bid to stave off civil war, but it will take time for the resources to be organised.