China's top Communist Party leader and former security czar Zhou Yongkang was today sentenced to life for graft, abuse of power and leaking state secrets in a closed-door trial, becoming the senior-most official to fall under President Xi Jinping's sweeping anti-corruption drive against "tigers and flies".



Zhou, 73, was sentenced to life imprisonment by Tianjin Municipal No. 1 Intermediate People's Court after the ruling Communist Party of China (CPC) charged him with the offences in April, breaking decades-old practice of not prosecuting retired top Communist Party leaders.



Zhou admitted his guilt following a secret trial in the northern city of Tianjin, about 120 kilometres from here, on May 22 and will not appeal, state-run Xinhua news agency reported about the verdict that was also read out on state television.



A glum looking Zhou with un-dyed hair was shown on the state television being brought to the court by police and later intently listened to the judgment read out to him.



"The basic facts are clear. I plead guilty and repent my wrongdoing," he said.



"Those involved, who bribed my family, were actually coming after the power I held, and I should take the main responsibility," he said before the judge.



"I broke the law and Party rules incessantly, and the objective facts of my crimes have resulted in grave losses of the Party and the nation," he said.



He said the handling of "my case in accordance with Party rules and the law reflects the authorities' determination to govern the Party strictly and advance the rule of law."



The court said Zhou leaked five "extremely confidential" documents and one "confidential" document to Cao Yongzheng, an unauthorised person, directly contravening the State Secret Law.



The court said Zhou's abuse of power and deliberate disclosure of state secrets were "in particularly grave circumstances," but his disclosure of state secrets "did not have very serious consequences."



Regarded as the most influential CPC leader until his retirement in 2012, Zhou oversaw China's security apparatus and law enforcement institutions, courts, police forces, prosecution agencies, paramilitary forces, and intelligence organs under Hu.



With today's verdict, Zhou has become the top-most CPC leader to be sentenced in China's recent history after Bo Xilai, party leader from Chongqing who was also sentenced to life in 2013 over charges of corruption, abuse of power as well as attempts to shield his wife for a murder.



Xi, 61, broke the norm as pressed ahead with the two-year anti-corruption campaign against "tigers and flies", meaning all ranks in order to restore the sagging credibility of the party among people.



Zhou's wife and son testified via a video link while Wu Bing and Jiang Jiemin appeared in court.



The court statement said Zhou had taken "particularly huge bribes," but had confessed, pleaded guilty and repented for his wrongdoing.



The majority of the money was accepted by his relatives, without his prior knowledge. Zhou asked his relatives to return their illegal gains. All gifts and cash have now been recovered.



These actions constitute "legal and discretionary grounds for lesser punishment."



The court reached its verdict "in accordance with the facts, nature, and details" of Zhou's crimes, based on the harm done to society.



Charged with "intentional" disclosure of state secrets, this trial was not open to the public.



The close aide of former President Hu Jintao was convicted for accepting bribes to the tune of 130 million yuan (USD 21.3 million), abusing power and deliberately disclosing state secrets.



Dubbed as a security czar for being the powerful Security Minister, Zhou was part of the nine-member Standing Committee of the ruling CPC, the highest decision-making body of the party from 2007 to 2012.



He held the post under Hu's administration -- the powerful post which enabled him to keep a tab on the CPC, including its top brass.



Zhou was so powerful that he was even accused of spying on Hu himself.