By Emma Farge and Gabrielle Tétrault-Farber

GENEVA (Reuters) -The U.N. Human Rights Council on Thursday narrowly passed a motion to increase monitoring of human rights abuses in Sudan, where hundreds of civilians have been killed since a conflict erupted last month.

Eighteen countries voted in favour of the Western-led initiative, 15 voted against and 14 abstained.

The motion had been backed by Western countries, including Britain and the United States, to condemn abuses by Sudan's warring factions, but many other countries voiced opposition.

No African country voted in favour of the initiative. Sudan's ambassador described the conflict as an internal affair and called for "African solutions for African problems."

Battles between Sudan's army and rival paramilitary forces have killed hundreds and wounded thousands, disrupted aid supplies, sent refugees fleeing abroad and turned residential areas of Khartoum into war zones since mid-April.

Western diplomats had predicted that the outcome of the vote - which grants the U.N.'s Sudan expert more powers to monitor abuses, among other measures - would be tight.

An African diplomat reported pressure from Arab states to oppose the vote on the basis that it could jeopardise ongoing Saudi Arabia-backed peace talks. No Arab country voted in favour of the initiative.

U.N. human rights chief Volker Turk told the 47-member Geneva-based council, the only body made up of governments to protect human rights worldwide, that both sides in Sudan's conflict had "trampled" on international humanitarian law

"There must be accountability for the horrific events taking place," Britain's Minister of State for Development and Africa, Andrew Mitchell, told the council by video link ahead of the vote.

China criticised the meeting while Pakistan's envoy said it risked exacerbating the situation. Sudan's ambassador Hassan Hamid Hassan poured scorn on the whole session.

"Why are you rushing to hold such an ad hoc session in this timing, especially since it has not received the support of any African or Arab countries," he asked.

"What's happening in Sudan is an internal affair and what the SAF (Sudanese Armed Forces) are doing is a constitutional duty to all armies in all countries in the world."

(Additional reporting by Gabrielle Tétrault-Farber; Editing by Andrew Heavens, Sharon Singleton and Christina Fincher)