Turkey says it has banned Syrian passenger planes from Turkish airspace in the latest sign of growing confrontation between the two neighbors.
Turkish authorities announced the ban on Sunday, four days after intercepting a Syrian passenger plane en route from Moscow to Damascus and confiscating what they said were military supplies on board.
Ankara has accused Damascus of using civilian airliners to bring in weapons for Syrian troops fighting an 18-month rebellion, and has vowed to prevent Turkish airspace from being used for such purposes.
Syria denounced Turkey's interception of the Syrian plane as piracy and retaliated Saturday, by closing its airspace to Turkish civilian aircraft. The move was largely symbolic as Turkey already had ordered its planes not to enter Syrian territory following Wednesday's incident.
Turkey has been one of the main regional supporters of the Syrian rebels trying to end Syrian President Bashar al-Assad's 11-year rule. Turkish forces also fired artillery into Syria for several days this month in response to Syrian shells that landed on the Turkish side of the border and killed five Turkish civilians.
In another development, U.S.-based rights group Human Rights Watch said Syrian government planes and helicopters have been dropping Soviet-made cluster bombs on populated areas across the country.
In a report published Sunday, it said residents reported finding remnants of the bombs in towns including Maarat al-Numan, which rebels seized earlier this month, cutting a key north-south supply route for government forces.
The Syrian government had no immediate response to the cluster bomb allegation.
Human Rights Watch arms director Steve Goose called on Syria to "immediately stop" all use of cluster bombs, which scatter small explosives over large areas and have the potential to kill and maim civilians for years. The rights group said video clips posted on the Internet last week show civilians holding unexploded bomblets, oblivious to the danger. It had no information on casualties.
Syrian state news agency SANA said government troops killed dozens of terrorists and captured rockets in Aleppo on Sunday. Syria refers to rebels as terrorists and accuses hostile foreign powers of arming them.
SANA also said a suicide bomber attacked a Damascus neighborhood on Sunday, but caused no other casualties.
U.N. and Arab League peace envoy Lakhdar Brahimi arrived in Iran on Sunday on the latest leg of a regional tour aimed at trying to defuse the Syrian civil war. Iran is Syrian President Assad's closest regional ally.