BEIRUT – The head of Syria's main opposition group in exile called Sunday for international powers to impose a no-fly zone in border areas to protect civilians who are coming under increasingly intense attacks by regime warplanes and helicopters.

The president of the Syrian National Council, Abdelbaset Sieda, told The Associated Press that such a move by the international community would show President Bashar Assad's regime that his opponents around the world are serious.

The Syrian opposition has been calling for a no-fly zone over Syria for months. But Sieda renewed the plea a day after U.S. Secretary of State Hillary Rodham Clinton said Washington and Turkey were discussing a range of steps including a no-fly zone over some parts of Syria as the regime increasingly uses its air force to attack rebels.