Zhang Chuanbin, former chief financial officer (CFO) of CCB International (Holdings) Ltd. China Construction Bank (CCB)'s investment arm, has been taken into custody by the police over possible involvement in a rat trading case, the CCB confirmed in a statement on Thursday.

Zhang was arrested at the CCB headquarter office in Beijing by officers from the Ministry of Public Security's Economic Crime Investigation Department on Dec. 31, according to a source close to CCB International.

Zhang allegedly carried out rat trading activities during the restructuring of Heilongjiang Heihua Co.,Ltd. It is estimated that Zhang obtained about 20 million yuan through illegal transactions.

China's business press carried the story above on Friday.