Waving Vietnamese flags and signs reading "Stop Violating Vietnam’s Territory," a couple hundred demonstrators moved from the Chinese Embassy through the capital’s streets surrounded by dozens of police and security forces. Hundreds more also protested in southern Ho Chi Minh City.

Protests are rare in Communist-run Vietnam and are typically quashed quickly by police.

Hanoi has responded feverishly following two incidents in the past month in which it accuses Chinese boats of halting Vietnamese hired vessels from conducting oil and gas exploration in waters off its central coast.

Vietnam says the incidents occurred within 200 nautical miles of its shores, within the economic exclusion area guaranteed by international law. It accuses Chinese boats of cutting cables used to conduct seismic surveys on vessels hired by state-run PetroVietnam.

But China responded harshly last week saying the latest clash occurred near the disputed Spratly islands, claimed by both countries along with several other Asian nations. It says the Vietnamese hired boat endangered Chinese fishermen’s lives.

Vietnam’s military exercise is expected to total nine hours Monday off the country’s central coast. Boats have been warned to stay out of the area during the drill, which appears to be an apparent response to the flare-up. It was the first time Vietnam has issued such an alert about maritime exercises.

A newspaper published by China’s ruling Communist Party ran an editorial Saturday warning Vietnam not provoke its much larger northern neighbor.

"If Vietnam insists on making trouble, thinking that the more trouble it makes, the more benefits it gains, then we truly wish to remind those in Vietnam who determine policy to please read your history," the editorial concluded. China once ruled over Vietnam for 1,000 years.

Vietnam and China have a long history of maritime scraps in disputed parts of the South China Sea near the Spratly and Paracel islands, which are teeming with fish and believed rich in oil and gas reserves.

The United States, which has said the South China Sea is in its national interest because of key international shipping lanes, has encouraged a diplomatic process to keep regional tensions from flaring.