Two French journalists missing in Syria must be released immediately, France's President Francois Hollande has said, according to BBC News.

Speaking in Japan, he said the men "do not represent any state" and were working "so the world can get information" on the conflict in Syria.

The men were named by their employer, French radio station Europe 1, as Didier Francois and Edouard Elias.

They had been travelling to Aleppo and had not been heard from in 24 hours, Europe 1 said.

Meanwhile, Austria has announced it is to withdraw its peacekeepers from the Golan Heights because of fighting between the government and rebel forces there.

The border clashes came a day after Syrian troops backed by Lebanese Hezbollah militants retook the key town of Qusair.