According to Sina Finance, the head of Europe's main banking regulator said supervisors are conducting additional risk reviews of banks' sovereign bond portfolios, which are worth trillions of euros.

Francois-Louis Michaud, chair of the European Banking Authority, said closer monitoring is needed as government bond yields in some core European countries have risen to multi-year highs. He said the risks still appear to be under control and added that banks have not shown signs of stress from current market moves.