Spokeswoman Rachael Dean confirms the Arizona Republican made the visit. She declined further comment about the trip.
The visit took place amid meetings in Paris involving efforts to secure participation of Syria’s fractured opposition in an international peace conference in Geneva.
And in Brussels, the European Union decided late Monday to lift the arms embargo on the Syrian opposition while maintaining all other sanctions against Bashar Assad’s regime after June 1, British Foreign Secretary William Hague said following the meeting.
Two years of violence in Syria has killed more than 70,000 people. President Barack Obama has demanded that Assad leave power, while Russia has stood by Syria, its closest ally in the Arab world.
McCain has been a fierce critic of Obama administration policy there while stopping short of backing U.S. ground troops in Syria, but he supports aggressive military steps against the Assad regime.
Gen. Salem Idris, chief of the Supreme Military Council of the Free Syrian Army, accompanied McCain across the Turkey-Syria border. McCain met with leaders of the Free Syrian Army from across the country, who asked him for increased U.S. support, including heavy weapons, a no-fly zone and airstrikes on Syrian government and Hezbollah forces, according to The Daily Beast, which first reported the senator’s unannounced visit.