15 policemen in south China's Guangdong province are under investigation after allegedly beating undercover journalists covering an official dinner that apparently flouted the country's ban on extravagant meals.

Journalists with Southern Metropolis Daily were going to report on public security officials feasting in a high-end restaurant in Shenzhen last week.

The paper said the reporters were beaten and robbed of their mobile phones and cameras, and that police who arrived at the scene later helped the officials get away.

28 people were served giant salamander at a dinner that cost about 5,400 yuan.

Giant salamander is a protected animal in China, but the policemen say what they had at the dinner was artificially-bred.

Chen Lewei, one of the journalists at the scene, says one of the officials confessed that they were consuming giant salamander.

"One of the officials attending the dinner came to us. He admitted that they were eating giant salamander, but added that the salamander was brought there by a friend from Guizhou."

In response to the scandal, the Shenzhen Municipal Public Security Bureau said that the incident took place at a local restaurant, to which a retired policeman from the bureau had invited his former colleagues.

The bureau added that Wang Yuanping, head of its Dongshen branch, is under police investigation on suspicion of "disciplinary violations."

It also promised an education campaign to ensure policemen abide by the law.

But the report has not revealed who actually paid for the dinner or who beat the journalists.