Scores have been jailed in the wake of rare nationwide demonstrations in Jun 2018 that quickly turned violent in some areas as police struggled to quell the unrest.

On Thursday, 15 people were sentenced to between two and 3.5 years in jail by a court in southern Binh Thuan province, where police stations were ransacked and security vehicles destroyed.

State-run Vietnam News Agency said "the 15 defendants were shouting, instigating the crowd" and blocked traffic on a major highway for 15 hours, citing the official indictment.

"The jury board concluded that the defendants' behaviour undermined security, order and social safety ... so they need to be seriously punished," VNA reported.

A court official confirmed the sentences and said several others are currently under investigation on similar charges, he told AFP, refusing to be named.

Last year's unrest was sparked by a proposal by the government to establish several economic zones with 99-year leases in the country that protesters said were designed to cater to Chinese investors.

The draft bill made no mention of China - and the government backed off the lengthy lease terms - but it was not enough to prevent the demonstrations in several cities, including Hanoi and the southern commercial hub of Ho Chi Minh City.

The bill has been shelved for now and officials have not said whether it may be revived.

China and Vietnam, who fought a bloody border war in 1979, have long had tumultuous ties and frequently spar over the disputed South China Sea.

This week a Chinese ship collided with a Vietnamese fishing boat in waters claimed by both Beijing and Hanoi, sinking the Vietnamese vessel and forcing the fishermen to scramble for safety on another ship, according to local press.

The investment zones were aimed at attracting foreign cash to the fast-growing, export-oriented economy.

The one-party state has clocked glittering growth in the past decade, while maintaining a firm grip on power.

Protests of any kind are banned and dissidents are routinely jailed.

Agence France Presse - March 7, 2019