HANOI, Vietnam – Vietnamese police have arrested four more former senior oil executives for allegedly abusing their power to appropriate property as the communist authorities step up their crackdown on corruption.

The arrests of the four who were former general directors or chief accountants of three subsidiaries of giant state energy firm PetroVietnam were made on Thursday, the Ministry of Public Security said in a statement.

Police were widening their investigation into the case to retrieve property to the state, it said.

The case involves Ocean joint stock bank, which gave $69 million in interest exceeding the rate set by the central bank to individuals and 400 companies and institutions including three subsidiaries of PetroVietnam.

PetroVietnam and the banking sector have been the centre of the government’s toughest crackdown on corruption in years.