SHANGHAI, Aug 18 (Reuters) - Tesla has shortened the delivery waiting time for the Model Y in China to four to eight weeks, it said on its Chinese website.

The U.S. automaker previously said a buyer in China needs to wait for eight to 12 weeks after placing an order for the best-selling model.

Tesla has completed a major upgrade of the production lines at its Shanghai plant and is ramping up weekly output to achieve 22,000 units of Model 3 and Model Y, Reuters reported earlier.

(Reporting by Zhang Yan and Brenda Goh; Editing by Tom Hogue)