The chief executive of China's Ant Group has stepped down "for personal reasons" as the online payment giant undergoes a restructuring.

Simon Hu will be replaced by executive chairman Eric Jing, the company said.

Ant is controlled by billionaire Jack Ma who first made his name through the trading platform Alibaba.

The firm has come under intense regulatory pressure and was forced to drop its planned $37bn public share sale last year.

Ant Group is China's biggest payments provider, with more than 730 million monthly users on its digital payments service Alipay.

But it also acts as a marketplace for loans. It takes a fee to match borrowers with banks, who then take on the risk.

It also offers savings accounts and insurance, all through its mobile phone app.

However Jack Ma has attracted controversy in China, criticising the state-dominated banking sector, and the company is in the cross-hairs of regulators, eager to bring it into line with more traditional banks and lenders, and to contain its market dominance.

Late last year the Chinese authorities blocked Ant Group's planned initial public offering (IPO) in Shanghai and Hong Kong.

Ant Group executives were told to restructure the company's operations to turn it into a holding company and to comply with stricter financial regulations.

Ant Group, formerly known by the name of its payments app Alipay, is affiliated with Alibaba, and like the Chinese trading platform has expanded its services outside its home country, including in Europe and the United States.