Apple's close relationship with China is getting ever closer. In the first quarter of the year, Apple's revenues in China rose 71 per cent to €14.7 billion, even though the overall market shrank by 4 per cent and the Cupertino-based tech firm overtook the domestic producer Xiaomi to become the largest seller of smartphones in the country.

Apple had 14.7 per cent of market share in the first quarter of 2015, compared to Xiaomi's 13.7 per cent share, according to data from the market researcher, International Data Corporation (IDC).

The two companies were followed by state-owned Huawei, then Samsung and Lenovo. In the first quarter, a total of 98.8 million smartphones were shipped, 4.3 per cent fewer than in the first quarter of 2014, the first drop in over six years, and a sign the market may be approaching saturation.

When Tim Cook was in China last week he said he was "very bullish" on the prospects of Apple Pay being introduced.

He met Alibaba founder Jack Ma during his visit and reportedly is in talks with Alibaba's Alipay, the largest Chinese electronic payment service to date.

Cook also signed up for the social media network Sina Weibo and within 24 hours had nearly half a million fans.