CAIRO, Jan 13 (Reuters) - At least 15 Yemeni civilians were killed in an air strike by a Saudi-led military coalition outside the capital, residents said on Wednesday, as prospects for a new round of U.N.-sponsored talks to end the war in Yemen dimmed.

A spokesman for the coalition said the reports of the air strike were inaccurate, without elaborating.

According to residents who spoke to Reuters by phone, the air strike hit an area near the village of Bilad al-Rus, around 40 km (25 miles) south of Sanaa, close to an army base for Houthi-allied Yemeni forces which have been fighting Saudi-backed troops in the conflict.

Twenty-five other people were wounded in the attack, they said. Families displaced by the nine months of fighting had been taking shelter in the area.

A mostly Arab coalition led by Saudi Arabia has been fighting the Iran-allied Houthis, who control the capital, since March of last year. Nearly 6,000 people are known to have died, about half of them civilians, according to U.N. figures.

The Houthis and Yemen’s embattled government agreed last month on a broad framework for ending their war in U.N.-brokered peace talks, but a temporary truce was widely violated and has since ended.

Another round of negotiations set for Jan. 14 was delayed, a U.N. spokesman announced on Tuesday, and may take place a week or more later as disputes over the venue and confidence-building measures persist.

Yemeni political sources said on Wednesday that U.N. envoy, Ismail Ould Cheikh Ahmed, has yet to achieve an agreement from the Houthi side to release the defence minister, General Mahmoud al-Subaihi, a key demand of President Abd-Rabbu Mansour Hadi’s government.

The Houthis say the Saudi-led coalition and government forces used the the last negotiations as a cover to make more military gains, and want a renewed ceasefire before new talks. (Reporting By Mohammed Ghobari; Writing by Noah Browning; Editing by Raissa Kasolowsky)