Tensions in the South China Sea heavily affected the company's oil and gas exploration and production activities in 2018, Voice of Vietnam radio reported, citing PetroVietnam Chief Executive Officer Nguyen Vu Truong Son.
Reserves at most of the company's operational fields are shrinking, the report said.
The company, formally known as Vietnam Oil and Gas Group, failed to raise its recoverable crude oil reserves as expected last year, it added.
The company did not immediately respond to a request for comment.
(Reporting by Khanh Vu; Editing by Edmund Blair)