China executed more people in 2016 than all other nations combined, Amnesty International said Tuesday, even as death penalties in the world decreased overall.
The human rights organisation estimates the Asian giant alone killed "thousands" of people, a figure based on examinations of court records and news reports.
All other countries together executed at least 1,032 people last year -- a decline of 37 percent compared to 2015. Of those, 87 percent took place in just four countries - Iran, Saudi Arabia, Iraq and Pakistan.
Amnesty's report found that hundreds of death sentences, including cases involving foreign nationals, had been omitted from China's public database of court verdicts, suggesting a concerted effort to hide the extent of the country's killings.
The ruling Communist Party considers the death toll a state secret.
"China is really the only country that has such a complete regime of secrecy over executions," Amnesty's East Asia director Nicholas Bequelin said at a press conference in Hong Kong.
"Probably the reason is the numbers are shockingly high, and China doesn't want to be a complete outlier in the world," he said.
Despite local media reports saying at least 931 individuals were executed between 2014 and 2016, only 85 of them were in the online database, Amnesty said.
In 2013, China's Supreme People's Court ruled that legal judgements should be made public, but the decision included many exceptions, including cases involving "state secrets" or personal privacy.
Previous estimates from other rights groups also put the number of annual executions in China in the thousands.
Chinese courts have a conviction rate of 99.92 percent, and concerns over wrongful verdicts are fuelled by police reliance on forced confessions and the lack of effective defence in criminal trials.