Prices of Bitcoin dropped by nearly 4 percent on Monday since Friday, down to a daily low of $7,739.37, according to Coindesk, a website following digital currencies.

Its price has decreased about 60 percent from the high of $19,511 on Dec 18, 2017, which has lost 26 percent in the past week and fallen 42 percent so far this year.

The roller-coaster fluctuations of cryptocurrency prices and the relevant illegal activities such as market manipulation, money laundering and defraud have raised Chinese financial regulators' concern. They are determined to crack down on ICOs and close all the domestic cryptocurrency trading platforms.

The crackdown has pushed some investors to shift their sights overseas and some Chinese investors continue to participate in cryptocurrency trading.

Li Honghan, a researcher at Zhongnan University of Economics and Law, said that "China's regulations on virtual currency will be further tightened, and measures may be launched soon to ban related commercial presences and close trading on both domestic and overseas platforms".

The National Internet Finance Association, the central bank-backed industry association, warned in January that lack of regulation in overseas markets makes ICOs and virtual currency trading risky and vulnerable, and may have potential risks like market manipulation and money laundering. It called on investors to pay attention to the risks of investing via overseas platforms.

According to a notice from the PBOC, payment institutions have been forbidden from providing services to cryptocurrency exchanges since last month.