BEIJING (Reuters) - China's institutional and individual investors should take a rational approach to investing in virtual currencies such as bitcoin, the central bank said on Friday.

Bitcoin prices had showed abnormal fluctuations, the Shanghai head office of the People's Bank of China (PBOC) said in a notice.

This prompted branch officials to meet representatives of a major bitcoin trading platform in China, BTCC.

They cautioned against potential risks in the platform's operations and asked it to carry out "self-inspection" according to the law, the bank said.

It stressed bitcoin is not a currency and cannot be circulated as a real currency in the market.

(Reporting by Yawen Chen and Kevin Yao; Editing by Clarence Fernandez)