Cambodia's war-crime tribunal on Wednesday started hearing closing statements in the trial of former senior Khmer Rouge leaders accused of masterminding the massacre of an estimated 1.7 million people during their regime from 1975 to 1979.

The accused persons on trial are ailing Nuon Chea, 86, also known as "Brother Number 2," former deputy secretary of the Communist Party of Kampuchea, and Khieu Samphan, 81, the regime's former head of state.

They are charged with war crimes, crimes against humanity and genocide, according to the Extraordinary Chambers in the Court of Cambodia (ECCC).

The closing statements have started with lawyers for the "civil parties" that represent the victims, followed by the statements from the prosecution and the defense.

"The closing statements will last until Oct. 31 and a verdict is expected in the first half of 2014," Dim Sovannarom, Chief Public Affairs Section at the ECCC, told Xinhua over telephone on Wednesday.

The Trial Chamber has sat for 212 hearing days since the commencement of opening statements in November 2011, the court said. Ninety-two individuals gave evidence during the trial hearings.

Launched in 2006, the United Nations-backed tribunal is seeking justice for an estimated 1.7 million people who died during the regime from 1975 to 1979.

In March, another defendant, Ieng Sary, former foreign minister of the regime, died on trial at the age of 87 due to illness, while the case against his wife Ieng Thirith, 81, ex-minister of social affairs during the regime, was suspended in September last year after the court ruled dementia left her unfit to stand trial.

To date, the tribunal has achieved only one conviction, sentencing ex-chief of Tuol Sleng prison Kaing Guek Eav to life in prison for overseeing the deaths of around 15,000 people during the regime.

The court is currently facing another setback due to budget shortages for Cambodian staff.