The Syrian government indiscriminately used cluster bombs in last week's attacks on civilian areas, according to a Human Rights Watch report released Sunday.

The news came as Turkey's foreign minister announced that the country is barring its airspace to civilian flights from Syria. As the AP reports:

"Ahmet Davutoglu said Sunday that Turkey had made the decision because the Syrian regime, which is battling an insurgency, was 'abusing' civilian flights by transporting military equipment."

Much of Syria's munitions are reportedly Russian-made; earlier this week Turkey forced a Syrian plane from Moscow to land on suspicions it was carrying Russian weaponry. Human Rights Watch says the cluster bombs used in recent attacks were Soviet-made.

Cluster bombs can scatter hundreds of "bomblets" over a wide area, not all of which may detonate immediately. They're considered such a danger to civilians that many countries banned their use under the 2008 Convention on Cluster Munitions. Neither Syria nor Russia have signed the convention.

"Syria's disregard for its civilian population is all too evident in its air campaign, which now apparently includes dropping these deadly cluster bombs into populated areas," said Steve Goose, the rights group's arms director.

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