Major crypto tokens dwindled back into the red after gains on Monday as analysts warned that bitcoin and ethereum prices are "in danger".
It came after reports that former bitcoin (BTC-USD) and ethereum (ETH-USD) miners in China have been dumping GPUs (graphics processing unit), which is responsible for the digital rendering in a computer system.
Bitcoin was down 0.4% to $33,708 (£24,335) after rising 2.7% to $34,340 on Monday morning in London. Other cryptos followed a similar path, ethereum fell 0.7% to $2,112 after edging 2.2% higher, and Tesla (TSLA) boss Elon Musk's favourite joke token, Dogecoin (DOGE-USD) fell 0.2% to $0.21 after gaining 2.6%.
Bitcoin has struggled to break above $36,000 in the last few days, but stayed above $32,000, and has recently been unable to either break upwards or correct downwards.
Chinese vice-premier Liu Hu promised in May that the nation would "severely crack down on illegal securities activities and severely punish illegal financial activities."
China extended the clampdown on the bitcoin mining industry to its biggest bitcoin producing provinces, including the southwest province of Sichuan, in June.
The People's Bank of China (PBOC) said last month that it had asked several major banks and payment firms to take tougher action over the trading of cryptocurrencies.
The Agricultural Bank of China, the country's third-largest lender by assets, said it would follow the guidance from the PBOC. It will also conduct due diligence on clients to root out illegal activities involving crypto mining and transactions.
Meanwhile, China's Postal Savings Bank also announced it would not facilitate any cryptocurrency transactions.
Cryptos also faced staunch opposition from global governments and central banks which have been keen to regulate digital currencies.
Last month the FCA issued a warning to consumers that one of the world’s largest bitcoin exchanges was not permitted to undertake regulated activities in the UK.
FCA ordered Binance Markets to remove all advertising and financial promotions by 30 June. Binance was required to make clear on its website, social media platforms and all other communications that it is no longer permitted to operate in the UK, and must not carry out any regulated activities in Britain without prior consent.
The UK's Advertising Standards Office announced it will start a major effort this month to remove misleading or irresponsible crypto ads, especially online.
Banks have also taken measures, Santander (SAN) told customers it will stop payments from accounts to Binance “wherever possible.” Binance is one of the world’s largest Bitcoin exchanges from operating in the country.
Similarly, Barclays (BARC.L) also said its customers will no longer be able to make credit or debit card payments to the crypto exchange after the ban.