UPDATE 2-Apple boss Tim Cook visits Shanghai with China sales under pressure

(Adds details on Cook's meetings on Wednesday paragraphs 1, 3-4)

SHANGHAI, March 20 (Reuters) - Apple CEO Tim Cook hailed China's importance in the firm's supply chain as he met suppliers including BYD Electronics on Wednesday, local media said, on a visit that comes amid a drop in China sales for the iPhone maker.

In a post on his Weibo social media account, Cook said he spent the morning walking along Shanghai's historic Bund river with Chinese actor Zheng Kai and that he had eaten a local breakfast. He did not disclose, however, what other plans he had for this China visit.

The China Daily reported that Cook had said in an interview that "there's no supply chain in the world that's more critical to us than China".

Cook also met Wang Chuanfu, founder and president of Apple supplier BYD Electronics, as well as officials from Lens Technology at the firm's Shanghai office, the China Daily added.

Cook's visit comes after the iPhone maker announced that it would open a new retail store in the heart of the Chinese financial hub on Thursday, and as Apple battles falling iPhone sales in China and rising competition from domestic rivals such as Huawei.

Cook made at least two visits to China, Apple's third-largest market by revenue, last year. He also travelled to Beijing around the same time last year, where he visited an Apple store and attended the China Development Forum. (Reporting by Beijing newsroom and Brenda Goh in Shanghai; Editing by Muralikumar Anantharaman and Miral Fahmy)