China's press watchdog has called on the public to report news stories they suspect of being fake by issuing two hotline numbers, in the wake of the mysterious "cardboard bun" scandal.

The General Administration of Press and Publication (GAPP) also asked all media institutions to set up and publicize their own hotlines to increase public supervision.

If a member of the public believes he has sniffed out a rat, he or she can call 8610-65212787 or 65212824, directly contact the news organization concerned, report to GAPP's press office by telephone or by clicking onto http://press.gapp.gov.cn, GAPP said in a notice.

The allegedly fabricated "cardboard dumplings" story which aroused public concern was produced by a Beijing Television reporter who, according to police, instructed four "baozi" -- stuffed buns -- cooks to fill their products with chopped waste cardboard earlier this month.

In the notice, the press watchdog reiterated that "authenticity was the lifeblood of journalism and ensuring authenticity of news reports was the basic professional ethic and a social responsibility borne by all journalists".

News organizations should tighten management of their staff and ensure all of them are qualified to be journalists. News reporters must conduct in-depth research and double-check news sources to prevent fabrication, GAPP said.