BEIJING (AFP) - Chinese prosecutors will be punished if officials they are investigating for abuse of office commit suicide, authorities said, after several suspects caught up in an anti-corruption drive killed themselves.

Under President Xi Jinping, a much-publicised anti-graft campaign has ensnared a long list of senior and junior officials. Some have committed suicide, escaping possible criminal proceedings and seizure of ill-gotten gains, to the benefit of their families.

In the latest example, the head of a multi-billion-dollar state-owned Chinese heavy machinery manufacturer was found hanging in his office on Monday as anti-corruption investigators probed his firm.

Respected business news outlet Caixin said in January that at least 50 party and government officials have been publicly declared to have died of "unnatural causes" since 2012.

The Supreme People's Procuratorate issued eight orders restricting how probes into acts of abuse of office, which often involve bribery or other forms of corruption, should be carried out.

Investigators will be suspended and "dealt with according to discipline and the law" if the subjects of their inquiries escape, are injured, or commit suicide because of their "unlawful" or "severely irresponsible" acts, it said in a statement on its website Thursday.

Prosecutors are also banned from accepting money from companies under investigation, unreasonably imposing coercive measures, or obtaining confessions through torture, according to the statement.

"The eight bans are prosecutors' code of conduct in their participation in the fight against corruption," it said.

"They will help build an anti-graft system that ensures justice, transparency and standards, and improve the effects and credibility of the anti-corruption campaign."

It vowed "zero tolerance" over violations of the rules, warning prosecutors and the police that the bans were "high voltage cables" that no one should "dare to touch".

In 2013, five Communist Party anti-graft investigators and a prosecutor in Wenzhou city were sentenced to four to 14 years in jail for drowning a state-owned company official reportedly stripped and held under water to try to extract a corruption confession.