State-run Vietnam Oil and Gas Group (PetroVietnam) said Tuesday that tensions in the South China Sea will hurt its offshore exploration and exploitation activities this year.

"The East Sea is forecast to continue to have uncertainty this year ... affecting the company's efforts to attract foreign investors to invest in its open offshore fields," PetroVietnam said in a statement on its website, using the Vietnamese name for the South China Sea.

Last month, PetroVietnam ordered Spanish energy firm Repsol to suspend its "Red Emperor" project off the country's southeastern coast following pressure from China, sources said.

Vietnam and China have been embroiled in maritime disputes in parts of the South China Sea, where China claims 90 percent of the potentially energy-rich maritime territory.