ViaBTC CEO Haipo Yang tweeted that “China will shut down all exchanges,” lending credence to the rumors that the country will make it illegal to operate a bitcoin exchange.

Earlier today, regional Chinese media outlet Caixin posted an article claiming that the country’s regulators are planning to ban bitcoin exchanges. These rumors are thus far unconfirmed, but Haipo Yang–CEO of bitcoin exchange and mining pool ViaBTC–tweeted that “China will shut down all exchanges,” along with a picture of what appears to be a news article. Yang has not commented further on the matter, nor has the official ViaBTC Twitter account revealed whether they have been shut down by the government.

China will shutdown all exchanges. pic.twitter.com/lmEiF0S5Eo — Haipo Yang (@yhaiyang) September 8, 2017

If the China bitcoin ban rumors are true, this would be the People’s Bank of China’s (PBoC) second move against the cryptocurrency industry in less than a week. On Monday, the bank declared initial coin offerings (ICOs) to be illegal, causing the crypto markets to temporarily crash.

Others, however, remain skeptical of the China bitcoin ban rumors. Blockstream CSO Samson Mow noted that the unconfirmed reports did not cite any official sources within the government. He suggested that if the PBoC intended to ban bitcoin, they would make an official announcement.

Would you believe news on CNN saying #Bitcoin is banned in the US without any statement or source from the SEC or CFTC? or NYDFS? — Samson Mow (@Excellion) September 8, 2017

According to Bloomberg China reporter Lulu Yilun Chen, bitcoin exchanges OKCoin and Huobi said they have not received shut down notices from the government and are still operating as normal. Regional cryptocurrency news source cnLedger contacted the exchanges and confirmed that they are functioning normally.

OKCoin also clarified this on their Weibo (Chinese Twitter):https://t.co/jiAJCFenlG — cnLedger (@cnLedger) September 8, 2017

Nevertheless, the PBoC has threatened bitcoin exchanges in the past, and today’s rumors caused the markets to flash crash.

Within a 10 minute period, the bitcoin price plunged by $400. BTC/CNY plunged below $3,800 on several exchanges, and the global average bitcoin price fell to $4,224. At present, bitcoin is trading at a global average of $4,363, according to data from CoinMarketCap, while CNY/BTC is still priced below $4,000 on OKCoin and BTCC.