BEIRUT (AFP) - A Syrian air strike on an Islamic State (ISIS) training camp in the jihadist-held east killed 17 militants and a child, a monitoring group said in a new toll Sunday.

The Saturday strike hit dormitories in the camp in the Euphrates valley town of Tibni in Deir Ezzor province, the Syrian Observatory for Human Rights said.

The child who was killed had been visiting his elder brother who was training with ISIS, the Observatory said.

President Bashar al-Assad's regime has stepped up its air campaign against the jihadists in recent weeks, carrying out near-daily air strikes against areas under their control.

The air force also hit jihadist targets in neighbouring Hasakeh province late Saturday, the Observatory said.

ISIS fighters have been battling both government troops and Kurdish militia in the north-eastern province, which has a large Kurdish population.

US President Barack Obama announced on Wednesday that he had authorised the expansion to Syria of the US air campaign against ISIS he launched in early August.

There have been no US strikes so far but Mr Obama's announcement, which was made in defiance of the Syrian government, drew protests from Damascus and its Iranian and Russian allies.