ISTANBUL » Turkish fighter jets shot down a Syrian warplane after it violated Turkey’s airspace Sunday, Turkey’s prime minister said, in a move likely to ramp up tensions between the two countries already deeply at odds over Syria’s civil war.

A spokesman for Syria’s military confirmed the incident, saying the plane was downed in Syrian airspace while attacking rebels. The unnamed spokesman quoted on Syrian state TV called the act a “blatant aggression,” and said the pilot safely ejected from the aircraft.

Turkey, once an ally of Syria, has emerged over the past three years as one of the main backers of Syrian opposition fighters trying to remove President Bashar Assad from power.

Turkish Prime Minister Recep Tayyip Erdogan, speaking at a rally in northwestern Turkey ahead of local elections on March 30, congratulated the Turkish military for protecting the border.

“If you violate our border, our slap will be hard,” he said.

According to Turkish news reports, the jet went down in a buffer zone along the border near an area where fighting has spiked in recent days.  Syrian government troops are trying to retake a border crossing point with Turkey near the town of Kassab that rebels captured Friday.

This is not the first time that the Turkish military has downed a Syrian aircraft near the border.

In September, a Turkish fighter jet shot down a Syrian military helicopter after it entered Turkish airspace. The helicopter strayed 2 kilometers (more than 1 mile) into Turkish airspace, but crashed inside Syria after being hit by missiles fired from the jet, Turkish officials said at the time.

Turkey changed its rules of engagement in 2012 after Syria shot down a Turkish military plane, declaring that any Syrian military element approaching the Turkish border would be treated as a legitimate target.