(Yicai Global) Sept. 12 -- As China's central bank works to improve its regulation of cryptocurrencies, major trading platforms have reinforced their anti-money laundering measures.

Btcchina.com, one of China's Big 3 bitcoin exchanges, is requiring some users to provide pay slips and other evidence about the source of their funds as well as explain how they plan to use withdrawn assets, The Beijing News reported today.

Some Btcchina.com users received e-mails asking them to fulfill the obligations for anti-money laundering policies by providing information on the source of their funds, a screenshot (of paystubs, etc.) as evidence and pictures of bank statements before they make a deposit.

They also need to describe how they use virtual currencies and provide appropriate evidence. If a trader makes a withdrawal to another platform, s/he may have to provide relevant records of it.