OREANDA-NEWS. December 06, 2013. China's oil giant PetroChina Co Ltd has received a notice from a U.S. court related to a complaint involving its former and current chairmen on suspected violations of U.S. securities regulations.

PetroChina, which with its parent China National Petroleum Corp has been embroiled in a major corruption probe by Chinese authorities, is unaware of amounts related to the complaint, it said in a filing to the Hong Kong and Shanghai stock exchanges.

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

"The company will vigorously contest the complaint with its best efforts to protect the legitimate rights and interests of the company," it said.

PetroChina also said the company was operating normally, without giving other details in the brief statement.

China has launched a slew of investigations into executives in various sectors, ranging from energy to shipping as President Xi Jinping focuses on rooting out graft, seen as a threat to the survival of the ruling Communist Party.

Last week, a court in northeastern China sentenced a former vice president of China Mobile Ltd's state-owned parent to life in prison for accepting prives, state media said.