A witness says Australian navy helicopter pilots were hit by lasers while exercising in the South China Sea, forcing them to land as a precaution.

Scholar Euan Graham, who was onboard the Royal Australian Navy flagship HMAS Canberra on a voyage from Vietnam to Singapore, said in an account of the incident that the lasers had been pointed from fishing vessels while the Canberra was being trailed by a Chinese warship.

China maintains a robust maritime militia in the South China Sea composed of fishing vessels equipped to carry out missions just short of combat.

Similar incidents involving lasers and the Chinese military have been reported as far away as Djibouti, where the U.S. and China have bases. Last year, the U.S. complained after lasers were directed at aircraft there.