ANKARA - Turkey will press on with its military operation in northeast Syria "with determination" after a U.S.-brokered ceasefire expires later on Tuesday if promises given by Washington have not been kept, President Tayyip Erdogan said.

Turkey says all Kurdish YPG militia forces must leave a "safe zone" it wants to establish along a section of its border with Syria. Ankara views the YPG as terrorists with links to Kurdish insurgents operating in southeast Turkey.

Speaking ahead of an official visit to Russia, Erdogan also said he would discuss with Russian President Vladimir Putin how a Syrian constitutional committee that is due to meet in late October can make concrete progress.

(Reporting by Mert Ozkan and Ali Kucukgocmen Writing by Ezgi Erkoyun Editing by Gareth Jones) ((ezgi.erkoyun@thomsonreuters.com; +90-212-350 7051; Reuters Messaging: ezgi.erkoyun.thomsonreuters.com@reuters.net;))