Vietnamese authorities have permitted a new protest against China in Hanoi as a maritime dispute between the two countries escalates.

About 100 people gathered Sunday in Hanoi, waving Vietnamese flags and shouting anti-China slogans. The protesters were surrounded by riot police and security personnel and dispersed peacefully after about half an hour. The demonstrators were also allowed to march through the streets of the Vietnamese capital.

Another protest took place in Ho Chi Minh City in the south of the country.

Public demonstrations are rare in communist Vietnam. But this is the second straight Sunday that the Vietnamese have demonstrated against China, after Hanoi lodged a protest with Biejing about China's alleged violation of Vietnam's sovereignty in the South China Sea.

The demonstrations took place ahead of live-fire naval exercises that the Vietnamese Foreign Ministry said will take place Monday off the central coast.

At issue is an area around uninhabited Paracel and Spratley islands in the South China Sea, which is believed to be rich in oil and gas reserves.

China, Vietnam, the Philippines, Malaysia, Brunei and Taiwan all claim South China Sea territories.

Taiwan's defense ministry said it is planning to send reinforcements to support the lightly armed coast guards on the disputed islands.

The Philippines also has accused China of trespassing in its territorial waters in the disputed region. But the government last week expressed hope that the dispute can be settled peacefully.