BEIJING - Chinese police said on Monday that they had arrested over 100 suspects for making a new type of "gutter oil" in a major food safety crackdown.

"Gutter oil" previously refers to the oil illegally made by reprocessing waste oil or even leftovers from restaurants, and then marketed and re-used as cooking oil which had aroused grave public concerns.

The new-type was made from dumped animal fat and then reprocessed into edible oil, said a statement issued by the Ministry of Public Security late Monday night.

It noted that the special operation had shut down 13 underground workshop and seized over 3,200 tonnes of such new-type "gutter oil".

More details was provided in a separate report from the China Central Television (CCTV) which further disclosed that those animal fat was waste fat from slaughter houses including rotten meat and animal viscera.

The ministry pledged to enhance the efforts in safeguarding food safety and battling related offences in the statement.

Several food safety scandals surfaced in 2011, including the "Gutter oil" and cancer-causing clenbuterol added pig feed to produce lean meat.

In response, China launched a nationwide food safety campaign in August 2011 to clamp down on such illegal practices, however the country's food safety authorities are still struggling to set up a reliable methods to verify "gutter oil".