Syrian government warplanes struck rebel outposts near the Jordanian border early on Tuesday, rebels said, bringing the war closer to Syria's U.S.-allied neighbor to the south.
The air strikes, at around 3 a.m. (0000 GMT) were the first near that part of the border, a Jordanian official said. They came hours after Syria's foreign minister warned Jordan against sending troops into his country.
Western-backed rebel groups fighting under the banner of the Free Syrian Army (FSA)'s so-called Southern Front have been active recently in the desert area near the borders with Jordan and Iraq, fighting Islamic State.
"The Syrian regime's jets conducted four strikes against us," said Tlas al-Salameh, the commander of Osoud al-Sharqiya, a Western-backed FSA faction which is the largest group operating in the Syrian Desert bordering Jordan.
Salameh said one air strike hit a border area where the rebel group shelters families of its fighters, others hit a rebel outpost 8 km (5 miles) from the Rukban camp where more than 80,000 refugees are stranded.