Police in Vietnam's capital, Hanoi, on Sunday arrested more than a dozen protesters denouncing Beijing's actions in the South China Sea.
The demonstrators were hauled away on buses after a brief demonstration near the Chinese embassy. Another group of protesters later gathered there, but police in riot gear dispersed them.
Demonstrators accuse China of violating Vietnam's territorial waters and harassing Vietnamese fishermen.
This was the latest in a series of Sunday protests against China in Vietnam's capital. The communist authorities do not normally permit street demonstrations.
The first few anti-China protests ended peacefully. But on Sunday July 10, authorities briefly detained several people, including journalists.
Rights groups have criticized Vietnam for arresting the protesters.
Last month, officials from Vietnam and China met in Beijing to discuss the maritime dispute and said they had agreed resolve their differences peacefully.
Vietnam says Chinese boats have hindered oil exploration within its economic exclusive zone, 300 kilometers off the coast.
Beijing accuses Vietnam of endangering Chinese fishermen in a contested area near the Spratly islands, which are claimed all or in part by both countries. The Philippines, Brunei and Taiwan also have territorial claims in the area, which is believed to be rich in natural resources, including gas and oil.