Three regime air strikes on rebel-held areas in the central Syrian province of Homs on Sunday killed nine civilians, six of them children, a monitoring group said.

Two strikes hit the village of Taldo in the Houla region, killing eight civilians including five children, said Syrian Observatory for Human Rights chief Rami Abdel Rahman.

A third strike targeted the nearby village of Kafrhala, also in the Houla region, and killed a child, said the head of the Britain-based monitoring group.

Rebel fighters, including Islamists, hold large parts of the northern Homs countryside where Sunday's strikes took place.

Houla was the scene of a May 2012 massacre when 108 people were killed, according to the United Nations, which said at the time that fewer than 20 died from artillery and tank fire and the rest were summarily executed.

Homs was at the forefront of the anti-government protests which erupted across Syria in March 2011, at the start of what has become a fully fledged war involving an array of local and foreign players.

The conflict has killed more than 310,000 people since it started, and more than four million Syrians have fled their homes.

On Monday, rebels and government representatives will for the first time sit around a negotiating table in the Kazakh capital Astana, for peace talks brokered by regime allies Russia and Iran and rebel backer Turkey.