Syria lashed out at Turkey and Jordan on Thursday for what it called their duplicitous work in fomenting the Syrian rebellion, accusing the Turkish prime minister of chronic lies and telling the Jordanians they were “playing with fire” in letting insurgents arm and train on their soil — a possible hint of retaliation.

The criticisms in the state news media appeared to be part of an intensified propaganda response to new rebel gains in the two-year-old conflict and President Bashar al-Assad’s further isolation.

It included snippets of an interview that Mr. Assad had given to a Turkish television station, in which he also denounced the Arab League for granting Syria’s seat to the opposition coalition bent on overthrowing him.

Turkey’s prime minister, Recep Tayyip Erdogan, who was once close to Mr. Assad, has turned into an ardent enemy and repeatedly called for his departure. Turkey is also housing more than 250,000 Syrian refugees and is helping the Free Syrian Army insurgent group, although the Turks insist they are not providing weapons. Syria, which shares a 550-mile border with Turkey, has frequently accused Turkey of arming the rebels.