China has told Vietnam to immediately stop unilateral oil exploration in parts of the South China Sea and not harass Chinese fishing boats, raising tension in protracted maritime territorial disputes with its neighbours.

Chinese Foreign Ministry spokesman Hong Lei made the statement in response to a question about Vietnam's state-owned oil and gas company's accusation that Chinese fishing boats sabotaged a seismic survey ship on Friday. Vietnam had already expelled Chinese fishing vessels from waters near China's southern Hainan province, Hong told reporters.

Hong has said the Chinese boats were carrying out "completely justified" fishing activities in an overlapping area between China's Hainan Island and Vietnam and were "unreasonably expelled by Vietnam."

Both countries are in negotiations about their overlapping claims in the South China Sea and that Vietnam should immediately stop unilateral oil exploration to allow a favourable atmosphere for talks, according to Hong.

China is in an increasingly angry dispute with neighbours over claims to parts of the potentially oil and gas-rich South China Sea. China lays claim to almost the whole of the sea, which is criss-crossed by crucial shipping lanes.