The CEOs of five Chinese Bitcoin exchanges have pulled out of the Global Bitcoin Summit, reports CoinDesk.

The chief executives of OKCoin, Huobi, BTC China, BtcTrade and CHBTC said they would no longer attend large-scale Bitcoin conferences and events.

In further bad news for the cryptocurrency, BTC China announced today that it had suspended yuan deposits from the Bank of China thanks to regulations.

All five exchanges issued a statement agreeing to reduce excessive speculation, safeguard investors, comply with all state regulations, pay a flat fee for high-frequency trades and report the latest industry developments to the relevant authorities.

The conference withdrawals will raise fears that the prospects for a flowering of Bitcoin in China are still on course to get worse before they get better.

In December last year, Bitcoin was dealt a severe blow when China banned financial institutions from trading in the cryptocurrency. Regulators stepped up the pressure by disallowing third party payment companies from buying or selling Bitcoin.

However, despite the hostile regulatory environment, some are still prepared to back the digital currency in the world's second largest economy.

In March, OKCoin announced a $10m Series A funding round. Venture Capital firm Ceyuan led the way and was followed by Mandra Capital, Ventures Lab and a string of other Angel investors. This amounted to one of the largest cases of Bitcoin financing so far. Smaller exchanges such as FXBTC have not been so lucky and have closed down in face of the the regulatory onslaught.

So far China has been an outlier in its hostility to the digital currency. Only 12 per cent of the 73 countries which have taken regulatory action toward Bitcoin are regarded as "hostile" or "contentious," in CoinDesk's State of Bitcoin report.