Vietnam has arrested four senior oil executives on allegations of abuse of power, in the latest arrests to target the country's corruption-plagued energy sector.
The communist leadership of Vietnam has zeroed-in on the country's largest oil firm, state-run PetroVietnam (PVN), and its subsidiaries in a massive anti-graft sweep that has already seen dozens jailed.
The corruption crackdown echoes a similar crackdown in China.
Critics say Vietnam's campaign is driven by a desire for reform -- and also by political infighting as communist leaders seek to tighten their grip on power.
The latest to be jailed include Tu Thanh Nghia, former director of Russia-Vietnam joint venture Vietsovpetro, and Vo Quang Huy, a former chief accountant at the firm, according to a statement from the Ministry of Public Security (MPS) late Thursday.
The two others arrested are Dinh Van Ngoc who used to run Binh Son Refining and Petrochemical Company and Nguyen Tuan Hung, the current chief financial officer of PetroVietnam Exploration Production Corporation.
All four are accused of "abusing power to appropriate property," the MPS statement said, without giving further details about the allegations.
"The case (will be investigated) under the direction of the central steering committee for anti-corruption," the statement said, adding the men would remain in custody during the probe.
State media said the men may have colluded with Ocean Bank -- another target of the government's anti-graft sweep -- to pocket excessive interest payments in a stitch-up with bank officials.
State media reported that Ocean Bank paid the firms involved a total of $5.1 million in excessive interest payments between 2010 and 2014.
Dozens of Ocean Bank employees have already been convicted for corruption, including former director Nguyen Xuan Son who was sentenced to death for embezzlement and economic mismanagement last year.
Former PVN executives have also not been spared.
Ex-chairman Dinh La Thang, who also served on Vietnam's powerful Politburo, was convicted in two separate graft trials last year and sentenced to a total of 31 years in jail.
He is currently appealing one of the sentences after he lost his first appeal bid last month.
Vietnam has vowed to polish its tarnished reputation as one of Southeast Asia's most corrupt countries. The anti-graft campaign has shocked a country unused to seeing high-flying executives publicly punished.