TAIPEI, Taiwan (AFP) — Prosecutors in Taiwan filed charges against 15 people and four companies on Tuesday over a cancer-causing substance found in cooking oil that prompted a recall and sparked political uproar.

More than 2,800 tonnes of oil have been pulled off shelves since Taiwan’s food regulator announced in early July that a batch produced by Central Union Oil Corp contained excessive levels of a hydrocarbon called benzo(a)pyrene.

Prosecutors in the central city of Taichung, where Central Union is based, accuse the company of stalling in reporting the contamination to authorities, and argue it had failed to issue a prompt recall as required by food safety laws.

Three companies that co-founded Central Union in 1995 have been accused of knowingly using the contaminated oil and selling it to consumers after repackaging or reblending it.

They “harboured malicious intent and disregarded public food safety”, the prosecutors said in a statement.

Opposition parties and President Lai Ching-te’s government have traded blame over the scandal, which has dominated local media headlines for weeks.

Thousands of people turned out at an opposition rally over the controversy, with calls for the premier and health minister to resign — which they refused to do.

The four companies have been charged along with six executives and nine employees, prosecutors said.

Prosecutors are seeking up to 14 years in prison and fines of up to NT$160 million ($5 million) under food safety regulations.