Seven people in north China's Hebei Province on Friday received jail terms of up to 15 years for manufacturing and selling "gutter oil."

Four managers of a cooking oil firm in the city of Xingtai and three other company staffers were convicted of selling 238.6 tonnes of dirty chicken salad oil for 2.05 million yuan (328,000 US dollars) in 2011, the Nanhe County people's court said in a verdict.

The unsafe edible oil was made from substandard chicken oil and animal oil used in animal feedstuff, according to the verdict.

The four managers were each sentenced to 15 years in prison and fined a total of 1.2 million yuan, it said.

One staffer was sentenced to two-and-a-half years in prison and fined 50,000 yuan. The other two staffers were given two-year jail terms and ordered to pay a fine of 60,000 yuan each.

"Gutter oil" refers to recycled oil made from kitchen waste dredged from gutters behind restaurants and other kinds of unsanitary animal oil. The oil is dangerous if consumed, as it contains carcinogenic substances.