Popular exchange BTC China has added new features and an upgraded interface to its Picasso ATM mobile bitcoin wallet, including a 'Sell for Cash' function that allows anyone to become a 'mobile ATM' and sell bitcoins anywhere in the world with the press of a few buttons.

CEO Bobby Lee announced the new features this morning while delivering the keynote address at the Inside Bitcoins conference in Hong Kong, where competitors OKCoin and Huobi are also revealing new services.

The app is designed as much for use outside China as inside, with support for eight major currencies and ten languages.

The 'ATM' function shows current market rates and allows users to set their own profit margin on the trade. BTC China receives a 0.5% transaction fee on a sale, deducted from the bitcoin balance.

Picasso mobile

also has the standard send and receive functions. As an HTML5 mobile web app, it was never subject to Apple's previous barring of bitcoin wallets.

BTC China

describes the surrounding infrastructure as offering users "the highest level of protection for their bitcoin assets", with a two-password option and all digital currencies stored offline.

Users more sure of their ability to not lose a device can be less cautious, enabling a 'Trust This Device' feature that does not require the main password every time the app starts.

BTC China, which was China's first bitcoin exchange and the first to receive venture funding, has been noticeable lately in its efforts to appeal to international customers due to China's own fractious relationship with digital currency trading.

Its website interface currently offers direct trades between Chinese yuan and both bitcoin and litecoin, and also between BTC/LTC. Following the Picasso ATM app's example, there are "plans for more aggressive international expansion" in the near future.

The Inside Bitcoins Hong Kong conference is a two-day event, which continues on 25th June.