Seoul, 26 May (IANS/AKI): Turkey and the US have in "principle" agreed to provide air support to mainstream Syrian rebels being trained and equipped to fight Islamic State militants, Turkish Foreign Minister Mevlut Cavusoglu said here on Monday.

"They have to be supported via air. If you do not protect them or provide air support, what is the point?" he told Daily Sabah newspaper during a visit to Seoul.

He did not go into details on what "in principle" meant or what kind of air cover would be provided or by whom.

The long-delayed scheme is meant to send 15,000 troops back to Syria but has been mired in delays amid reports of disagreements between the two NATO allies.

Turkey says its support for scheme is conditional on a comprehensive strategy that includes battling forces loyal to Syria's authoritarian president Bashar al-Assad.

While opposing Assad, the US maintains the goal of the training is only to defeat IS in Syria. US officials have said the aim is to train 5,000 Syrians a year for three years at a base in the central Turkish city of Kirsehir and at sites in Saudi Arabia and Qatar.

Ankara and Washington agreed in February to train and equip the Syrians under a $500 million US programme.