BEIJING - Chinese police have arrested 32 suspects for producing and selling illegal cooking oil in a cross-province crackdown, the Ministry of Public Security said in a statement Tuesday.

More than 100 tonnes of such oil, made from leftovers dredged from gutters behind restaurants, were seized after busting a criminal network spanning 14 provinces, the ministry said.

Police began their investigation in March after residents in Ninghai County of eastern Zhejiang Province reported that a group of people were buying leftover oil from local restaurants.

The 32 suspects were caught in a cross-province crackdown launched in mid-July,when police from Zhejiang, Shandong and Henan jointly removed six underground producing sites and uncovered two illegal-production lines in the provinces, according to the statement.

In the statement, the ministry pledged it will eliminate the illegal cooking oil market.