REYHANLI, Turkey A car exploded at a crossing on Turkey's border with Syria near the Turkish town of Reyhanli on Monday, killing at least nine people including Turkish citizens and wounding dozens more, officials said.
Witnesses said they saw the car drive up to the Cilvegozu border post, one of the main crossing points for Syrian refugees into Turkey, shortly before the explosion.
"We don't know whether this was a suicide bomb or whether a car that was smuggling petrol across the border blew up," one Turkish official told Reuters.
The mayor of Reyhanli told CNN Turk that nine people were killed, four of them Turkish, and that the car which exploded had Syrian licence plates.
Television footage and photographs showed severe damage to a series of vehicles at the border, where a gate was blown open and part of the roof collapsed.
Turkey is a staunch supporter of the near two-year uprising against Syrian President Bashar al-Assad and has harboured both Syrian refugees and rebels. Violence has sometimes spilled over the border.
Five Turkish civilians were killed in October when a mortar shell hit a house in the Turkish border town of Akcakale.
Turkey has also responded in kind to gunfire and mortar rounds hitting its territory along the 910-km (565-mile) border and is hosting six NATO Patriot missile batteries meant to defend it against attacks from Syria.
Tensions have increased in recent weeks after NATO said it had detected launches of short-range ballistic missiles inside Syria, several of which have landed close to the Turkish border. Turkey has scrambled warplanes along the frontier, fanning fears the war could spread and further destabilise the region.
Prime Minister Tayyip Erdogan interrupted a cabinet meeting to be briefed on the explosion, Turkish media reported.
The Cilvegozu border gate, several kilometres outside Reyhanli, sits opposite the Syrian gate of Bab al-Hawa, which the rebels captured last July.
Refugees cross back and forth and Turkish trucks also deliver goods into no-man's land between the two gates, where they are picked up by Syrians.
Speaking from scene, Syrian opposition campaigner Osama Semaan said he believed the explosion was an attack by Assad loyalists in response to an offer of talks from opposition Syrian National Coalition leader Moaz Alkhatib.
"It seems it is a deadly message from the Syrian regime after Sheikh Moaz offered it to talk in northern Syria," Seeman said.
Alkhatib said on Sunday he was willing to hold talks with Assad's representatives in rebel-held areas of northern Syria to try to end a conflict that has killed some 60,000 people.
(Reporting by Jonathon Burch and Ozge Ozbilgin in Ankara, Daren Butler in Istanbul, Khaled Oweis in Amman; Writing by Nick Tattersall; Editing by Jon Hemming)