BEIJING - Customs at China's northern Dalian port has banned imports of Australian coal and will cap overall coal imports for 2019 through its harbours at 12 million tonnes, an official at Dalian Port Group told Reuters on Thursday.

The indefinite ban on imports from top supplier Australia, effective since the start of February, comes as major ports elsewhere in China prolong clearing times for Australian coal to at least 40 days.

Five harbours overseen by Dalian customs - Dalian, Bayuquan, Panjin, Dandong and Beiliang - will not allow Australian coal to clear through customs, said the official. Coal imports from Russia and Indonesia will not be affected.

The ports handled about 14 million tonnes of coal last year, half of which was from Australia, said Gu Meng, analyst at Orient Futures.

The Dalian official declined to be named due to the sensitivity of the matter. Dalian customs did not immediately respond to a request for comment.

(Reporting by Meng Meng, Muyu Xu and Dominique Patton; editing by Richard Pullin) ((dominique.patton@thomsonreuters.com; +86 10 6627 1027; Reuters Messaging: dominique.patton.thomsonreuters.com@reuters.net))