BEIJING (AFP) - China's former security chief Zhou Yongkang was charged Friday with bribery, abuse of power, and intentional disclosure of state secrets, the official Xinhua news agency reported, setting the stage for a dramatic trial.

Zhou, who had a background in the oil industry, was a member of the Communist Party's elite Politburo Standing Committee and is the highest-ranking Chinese official to be prosecuted since the Gang of Four in the 1980s.

"The defendant Zhou Yongkang... took advantage of his posts to seek gains for others, illegally took huge property and assets from others, and abused his power, causing huge losses to public property and the interests of the state and the people," Xinhua cited the indictment as saying.

It was filed with a court in the northern port of Tianjin, it added. After months of rumours, party authorities announced last July they were investigating Zhou, who accumulated vast power until he retired in 2012.

Zhou was expelled from the ruling party and formally arrested in December. His fall sent shockwaves through the ruling party, and made him the most prominent victim of President Xi Jinping's much-publicised anti-corruption drive, which has targeted high-level "tigers" as well as low-level "flies".

But critics note that China has failed to implement institutional safeguards against graft, such as public asset disclosure, an independent judiciary, and free media, leaving anti-graft drives at risk of being used for political faction-fighting.

China's ruling party is riven by factional divisions but consistently seeks to present a united front to outsiders.

Several of Zhou's allies have also been brought down in the campaign, among them Jiang Jiemin, the former head of the body that regulates China's state-owned firms.

He is a former head of the China National Petroleum Corporation, a post previously held by Zhou, and the two are reportedly part of a Communist Party faction with roots in the oil industry, known as the "petroleum gang".