ISTANBUL (Reuters) - World powers have not ruled out Turkey's idea for a "safe zone" in Syria but they have not shown a clear will to implement the plan either, the spokesman for Turkish President Tayyip Erdogan said on Tuesday.

Ibrahim Kalin also told broadcaster NTV that Erdogan was pushing for an initial 48-hour ceasefire in the northern Syrian city of Aleppo with the plan to extend that through the Muslim Eid al Adha holiday, due to start around Sept. 11.

Erdogan had said on Monday that he repeated Turkey's proposal at a meeting of G20 leaders for a "safe zone" from fighting in Syria to help curb the flow of migrants.

(Reporting by Humeyra Pamuk; Writing by Edmund Blair; Editing by Nick Tattersall)