The Japanese government said on Monday it was doing all it could to secure the release of a Japanese journalist being held hostage by an al-Qaida affiliate in Syria, after an apparent photograph of the man was posted on the internet.

The photograph, apparently uploaded to the internet late on Sunday, showed a bearded man dressed in orange holding a handwritten sign in Japanese.

"Please help me. This is my last chance," said the sign, written in shaky characters and signed "Jumpei Yasuda".