ISTANBUL (AFP) - The baby of a French woman of Syrian origin died on a Turkish plane while his mother was being deported to France from Turkey over suspected ties to the Islamic State in Iraq and Syria (ISIS) group, diplomatic sources said on Thursday.

Five-month-old Muhammed al-Amin Mahiev died of heart failure while travelling with his mother Iman Mahiev on an internal Turkish Airlines flight from the southeastern city of Gaziantep to Istanbul, a diplomatic source in Turkey told AFP.

From Istanbul, they were both to have been be put on another plane for France.

Both are French citizens.

The mother was being deported to France after being detained by the Turkish authorities close to the Syrian border over suspected ties to ISIS militants, the diplomatic source said.

The baby had been born premature.

Turkish media reports said that despite efforts to save him, the baby died just after the plane landed at Istanbul's Ataturk Airport.

The mother and son had been escorted on board the Gaziantep-Istanbul flight by Turkish police officers.

Gaziantep lies just near the border with Syria and has in the past been a major gateway for those seeking to link up with ISIS extremists whose strongholds are in the northern part of the war-torn country.

Long criticised for not doing enough to stem the flow of militant fighters across its volatile border with Syria, Turkey stepped up the fight after a number of deadly attacks on Turkish soil blamed on ISIS, making almost daily arrests of would-be militants.

The Turkish security forces regularly detain foreigners along the border with Syria then deport them back to their home countries.