A steel company owned by the Taiwanese giant Formosa Plastics has accepted full responsibility for a chemical leak that killed huge numbers of fish in Vietnam in April.

Key points: Taiwan steelmaker and Vietnamese Government admit to a pollution event caused a mass fish kill

Taiwan steelmaker and Vietnamese Government admit to a pollution event caused a mass fish kill Protesters were beaten and arrested in April when seeking answers

Protesters were beaten and arrested in April when seeking answers Government says cyanide, phenol and ferrous hydroxide toxins leaked into the ocean

The Vietnamese Government has also admitted that the steel factory was the cause of a the mass fish kill after denying any such link for months.

The accident was one of Vietnam's worst environmental disasters, a chemical spill that left 200 kilometres of coastline littered with dead fish.

Previously the company denied its steel plant had caused the mass poisoning, and the Vietnamese Government also said there was no link. Both have dramatically changed their stories.

When Vietnamese people protested about the massive fish kill in April its Government cracked down hard, arresting more than 500 people and beating some of the demonstrators.

At a media conference, a Government official played a video clip of the chairman of Formosa Ha Tinh Steel expressing regret and saying his company accepted "full responsibility".

"Violations in the construction and testing operations of the plant are the causes for serious environment pollution killing a massive amount of fish," Government office chief Mai Tien Dung said.

The damage was apparently caused by the testing of a new wastewater system at the steel plant.

The company promised to pay $670 million in compensation.

The Government said that the latest findings found the toxins that leaked into the ocean were cyanide, phenol and ferrous hydroxide.

Government officials denied engaging in any cover-up to protect a big investor and said the delay in reaching a conclusion was to ensure certainty.

ABC/Reuters