BEIJING - The Chinese authorities have seized assets worth at least 90 billion yuan (S$18.3 billion) from family members and associates of retired domestic security czar Zhou Yongkang, who is at the centre of China's biggest corruption scandal in more than six decades, two sources said.
More than 300 of Mr Zhou's relatives, political allies, proteges and staff have also been taken into custody or questioned in the past four months, the sources, who have been briefed on the investigation, said.
The sheer size of the asset seizures and the scale of the investigations into the people around Mr Zhou - both unreported until now - make the corruption probe unprecedented in modern China and would appear to show that President Xi Jinping is tackling graft at the highest levels.
But it may also be driven partly by political payback after Mr Zhou angered leaders such as Mr Xi by opposing the ouster of former high-flying politician Bo Xilai, who was jailed for life in September for corruption and abuse of power.
Mr Zhou, 71, has been under virtual house arrest since the authorities began formally investigating him late last year. He is the most senior Chinese politician to be ensnared in a corruption investigation since the Communist Party swept to power in 1949.
"It's the ugliest in the history of the New China," said one of the sources, who has ties to the leadership, requesting anonymity to avoid repercussions for speaking to the foreign media about elite politics.
A source with ties to the leadership said Mr Zhou had refused to cooperate with investigators, insisting he was the victim of a power struggle.
"Zhou Yongkang is tough and claims it's political persecution," the source said.
Mr Zhou rose through the ranks of China's oil and gas sector before joining the elite Politburo Standing Committee in 2007 where, as domestic security chief, his budget exceeded defence spending. He retired in 2012 and was last seen at an alumni event at the China University of Petroleum on Oct 1.
Sources said prosecutors and the party's anti-corruption watchdog had frozen bank accounts with deposits totalling 37 billion yuan and seized domestic and overseas bonds and stocks with a combined value of 51 billion yuan, after raiding homes in Beijing, Shanghai and five provinces.
Investigators had also confiscated about 300 apartments and villas worth around 1.7 billion yuan, antiques and contemporary paintings with a market value of 1 billion yuan, and more than 60 vehicles, the sources added.
Other items seized included expensive liquor, gold, silver and cash in local and foreign currencies.
The seized assets belonged to those in custody, the sources said, without saying how many people in total had been detained, compared to just questioned. Most of the assets were not in Mr Zhou's name, they added.
The amount eventually made public could be smaller, to avoid embarrassing the party and angering ordinary Chinese, the sources said.
Sources added that more than 10 of Mr Zhou's relatives had been detained. They included his brother, his one-time television-reporter wife Jia Xiaoye, his eldest son from a previous marriage Zhou Bin, and Zhou Bin's in-laws.