The Malaysian Consumer Protection and Welfare Board wants the government to monitor manufacturers which it claimed had sold recycled cooking oil to consumers.

Deputy President Dr Lee Nan Sang said syndicates had been carrying out such activities and the problem has exacerbated following higher demand for cheaper cooking oil sold in packets.

"The sale of used cooking oil, mixed with new ones, had gone on for a long time. It is a big industry and the people involved had made millions of ringgit in profits."

"This syndicate has been running rampant. They buy used cooking oil, have it processed and resold in packet form," Dr Lee told reporters at the board's headquarter's on Monday.

He also questioned the halal status of recycled cooking oil.

"The recycled oil comes from different sources - hotels, restaurants and homes. We are not aware of its previous usage. So, when the oil is used to cook non-halal food, the recycled oil might also be non-halal."

Dr Lee has urged agencies such as the Domestic Trade, Cooperatives and Consumerism Ministry (KPDNKK) to produce a list of cooking oil manufacturers that complied with standards.

The matter, he said, should not be taken lightly as research has shown that consuming recycled cooking oil can cause illness.

Dr Lee also urged consumers to report to regulators on individuals suspected to be involved in the syndicate or should they find the quality of cooking oil questionable.