A Chinese journalist who had been following a scandal involving the sale of cooking oil made from leftovers taken from gutters has been stabbed to death, police and state media said Tuesday.

Li Xiang, 30, a reporter with Luoyang Television Station in the central province of Henan, was knifed more than 10 times early Monday as he returned home from a karaoke session with friends, the Zhengzhou Evening News reported.

The laptop computer Li had been carrying was missing and police were treating the case as a murder-robbery, but have not ruled other motives, the report added.

Police told AFP that Li "died in the early morning of September 19" but declined to comment further as the case was still under investigation.

An editor at the television station declined to comment when contacted by AFP.

Li, who was due to be married in October, had apparently been following the latest food scandal to hit China, a "gutter" cooking oil scam which has led to the arrests of 32 people caught selling the carcinogenic product.

Police in Henan and the eastern provinces of Zhejiang and Shandong have found more than 100 tonnes of the recycled oil illegally made from leftovers taken from gutters, the Ministry of Public Security said in a statement.

The last post on Li's micro-blog on September 15 said web users "had complained that Luanchuan county (in Henan) has dens manufacturing gutter cooking oil, but the food safety commission replied that they didn't find any".

Bloggers said they suspected Li's death was related to his previous reports on the "gutter" cooking oil cases.

"Luoyang Television Station reporter Li Xiang got stabbed to death, I suspect it's related to his reports on 'gutter' cooking oil," a web user said on Sina's popular social networking site Weibo.

"Li Xiang's stabbing death is the unfortunate outcome of investigating the gutter cooking oil cases," another user said.