BEIJING (AFP) – China on Wednesday executed a former top police and justice official at the centre of a huge graft and organised crime scandal that riveted the nation, state-run Xinhua news agency reported.

Wen Qiang, 54, the former head of the judiciary in the southwestern Chongqing region and also an ex-deputy police chief, was sentenced to death in April for charges including rape and taking bribes to protect criminal gangs.

He was executed in Chongqing, Xinhua said, giving no other details on the manner of his execution.

China, which rights groups believe executes more people each year than the rest of the world combined, has traditionally performed executions with a bullet to the back of the head but lethal injections have found increasing use.

Wen's case brought to a climax a crime crackdown that lifted the lid on the seamy underworld in Chongqing, a mega-city of more than 30 million people, and highlighted China's problem of rampant official corruption.

The crackdown has resulted in more than 3,300 detentions and hundreds of prosecutions, including the trials of nearly 100 officials.

Several people have already been reported executed or sentenced to death in the trials, which shocked the public by exposing the impunity enjoyed by Chongqing mafia bosses and the corrupt officials who protected them.

The trials engrossed the public due in no small part to the salacious details revealed in court. Wen allegedly raped a number of women including B-list film and music starlets, and had affairs with subordinates.

Wen -- who was deputy police chief for 16 years -- also was found guilty of taking more than two million dollars in bribes and engaging in a range of corrupt activities.

He owned numerous flats and villas, had a fleet of foreign luxury cars, and maintained a treasure trove of antiques and artworks worth hundreds of millions of yuan, press reports said.

At his February trial, Wen admitted he took money from others on numerous occasions but said that no corruption was involved and much of it was for "birthday and New Year" greetings, according to state media.

Wen was tried with his wife, Zhou Xiaoya, and three former Chongqing police associates, all of whom received jail sentences of up to 20 years.

Last November, Wen's sister-in-law Xie Caiping was sentenced to 18 years in prison on charges of running illegal gambling dens and drug dealing. She reportedly drove a Mercedes-Benz, owned several luxury villas and kept a stable of 16 young men to provide her with sexual services.

The crackdown is widely seen as a bid by Bo Xilai -- who was appointed party secretary in Chongqing in 2007 and is considered one of the party's most popular and charismatic figures -- to move up in the national hierarchy.