A steel company has taken full responsibility for an enormously destructive chemical leak this year.

The spill - one of Vietnam's worst environmental disasters – left dead fish littering over 200 kilometres of.

The company - which is owned by the Taiwanese giant Formosa Plastics - had been denying that the steel plant caused the mass poisoning, and the Vietnamese Government denied the link too.

Now both parties have admitted that the factory caused the mass fish death.

The damage was caused during the tests of a new wastewater treatment system, which saw large amounts toxins leaked into the ocean including cyanide, phenol and ferrous hydroxide.

The spill will cost the company over $670 million fines and compensation.

More than 500 people were beaten and arrested during a protest by Vietnamese people protested about the mass poisoning.

The chairman of Formosa Ha Tinh Steel expressed regret and accepted “full responsibility” in a pre-recorded video message played by a Government official at a media conference this week.

“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.

Government officials denied involvement in a cover-up to protect one of the nation’s largest investors.