Hanoi (AFP) - Vietnam arrested another activist on Monday for organising protests over mass fish deaths caused by pollution from a steel plant, the same day a lawmaker resigned over the environmental scandal.
Taiwanese steel firm Formosa was blamed for pollution last year which killed tonnes of fish, including rare species, and decimated livelihoods in coastal fishing communities in central Vietnam.
The firm, which was in the process of building the plant, was fined $500 million over the disaster.
But anger still seeths in coastal communities and regular protests have continued since the fish kill in April last year.
Vietnam -- an authoritarian one-party communist state -- has cracked down on the protests and arrested leaders.
Police in the central province of Nghe An on Monday detained activist Hoang Duc Binh on charges of "causing public disorder and abusing his democratic freedom to infringe upon the state's interests".
Binh, 34, was accused of organising fishing communities, provoking local fishermen and Catholics to stage regular protests including a recent demonstration outside a police station.
His detention sparked hundreds of local residents in Nghe An province to gather and demand his release with images on social media showing hundreds of police being deployed to the scene.
State controlled Vietnam Television said three policemen briefly taken hostage by the crowds were later released.
Around the same time Vietnam's rubber-stamp National Assembly accepted the resignation of lawmaker Vo Kim Cu over the fish deaths, part of a carefully choreographed punishment that has been laid on for a number of officials implicated in the disaster.
Last month Cu and three other officials were stripped of their party positions over the Formosa scandal.
The Party Secretariat said Cu made multiple violations including failing to adequately monitor the implementation of the steel plant.
While Formosa has been fined, it has been given a green light to restart operations.
Last month Vietnam said it could test the plant's first blast furnace for a six month trial period.
Formosa completed 17 environmental protection checks and had adequately addressed most of the violations required to operate after the disaster, according to Vietnam Television.