(Yicai Global) Aug. 3 -- For businesses to reject cash in yuan is illegal, an official from China's central bank said.

Yuan is China's legal currency, Shanghai Securities News quoted an official from the People's Bank of China as saying today. Enterprises may decline bank card and third-party payments, the official said.

Mobile transactions have become increasingly popular and some establishments in major Chinese cities have refused to accept cash, saying they only take mobile payments.

The value of the country's third-party mobile payments more than doubled to USD5.5 trillion (CNY38 trillion) last year, market research firm iResearch estimated. Tencent Holdings Ltd.'s [HKG:0700] WeChat Wallet and Alibaba Group Holding Ltd.'s [NYSE:BABA] Alipay dominate the Chinese mobile payment market.

In the US, mobile payments grew 39 percent to USD112 billion. The market is shared by Apple Inc. [NASDAQ:AAPL], Alphabet Inc.'s [NASDAQ:GOOGL] Google, Samsung Group and PayPal Holdings Inc., Forrester Research data shows.