A total of 711 convicts, including 76 corrupt officials above bureau level, have been returned to prisons to complete their sentences under the supervision of prosecuting departments, amid an intensified crackdown on illegal commutations of sentence or conditional releases, a senior official from the Supreme People's Prosecutorate said on Tuesday.

"Apart from receiving tips reported by the public and the media, we have been conducting active investigations to discover criminal signs," said Yuan Qiguo, director of the prison management bureau of the SPP.

Figures released by the SPP show that, since March, national prosecutors have found 428 pieces of information involving the illegal reduction of sentences, release on parole or sentences being served outside of jail.

They have also investigated 120 law enforcement officers involved in 105 cases on suspicion of dereliction of duty or abuse of power to help offenders obtain reduced sentences or conditional release, in return for huge bribes, the figures show.

In March, the top prosecuting department initiated a nine-month campaign across the country to target such crimes, especially for corrupt officials, criminals with major economic crimes, mafia-like gang members or those involved with violent and terrorist attacks.

The campaign will last until the end of this year.