AMMAN (Reuters) - A suicide bomber killed at least 12 people when he blew himself up on Thursday at the opening of a local police station in a rebel-held town in southern Syria, rebels and residents said.

Those killed included a member of the Western-backed opposition interim government, they said.

They said the bomber, a young man, detonated his suicide vest just as local officials were gathering to inaugurate the police station in the town of Inkhil, 40 kms (25 miles) north of the city of Deraa, the provincial capital.

The minister of local administration in the Western-backed interim Syrian government, Yaqoub al Amar, was killed in the explosion along with several local officials, a resident said.

Issam al Rayes, a spokesman of the Western-backed Free Syrian Army, said the signs were that either Islamic State "or agents of the Syrian authorities" were behind the attack.

Amaq news agency which is affiliated to Islamic State cited a security source as saying one of its fighters had detonated his vest during what it said was a meeting of opposition figures in the town. It did not give a number of those killed in the blast.

(Reporting by Suleiman Al-Khalidi; Editing by Richard Balmforth)