China’s oil giant, PetroChina Company Limited (NYSE:PTR), received notice of an investigation from a U.S. court on after being alerted to suspicion that former and current heads of the company may have violated U.S. security regulations, Reuters reported Tuesday.

An overseas shareholder filed the complaint with the U.S. District Court for the Southern District of New York against ex-Chairman Jiang Jiemin, current Chairman Zhou Jiping, former Chief Financial Officer Zhou Mingchun and current CFO Yu Yibo.

PetroChina, which is involved in a major corruption investigation by Chinese authorities, said it's are unaware of amounts related to the complaint.

Back in September PetroChina was hit by a U.S. class action law suit for failing to disclose a graft probe and misleading investors by failing to disclose it was being proved for corruption