Pig farmers will 'Aku janji' oaths pledging not to use banned growth enhancers on livestock amid a government crackdown on illegal farming substances.

Health Minister Chua Soi Lek said all 656 pig farmers in the country would vow to stop using banned growth boosters such as beta-agonist, a medicine used to treat asthma patients that can be fatal when consumed in pork.

"They will have to appear before a commissioner of oaths," Chua was quoted as saying in the New Straits Times . "Once the pledge is signed, it will be easier to take legal action if they flout the ban."

Chua said the government was trying to persuade butchers to sign similar pledges, the Star daily newspaper reported.

Pork tainted with illegal substance

Malaysia in December quarantined 30 pig farms for one month after pigs tested positive for beta-agonist.

Chua said at the time that about 70 percent of pork sold in Kuala Lumpur was tainted with beta-agonist, which was banned 10 years ago. The substance has also reportedly been found in beef, mutton and duck meat.

When consumed in pork, beta-agonist causes headaches, dizziness, palpitations and breathing difficulties in humans, and can be fatal for those suffering from heart-related disease.

Pork vendors found selling meat containing the substance face fines of up to RM100,000 or 10 years in jail.