Singapore's attorney-general on Friday issued a stern warning to an independent filmmaker over online videos in which two Chinese bus drivers accused police in the city-state of assaulting them.

Lee Seng Lynn had released videos of her interviews with He Jun Ling, 32, and Liu Xiang Ying, 33, in January.

The two were among four Chinese nationals subsequently sentenced to jail terms of up to seven weeks for organising Singapore's first industrial strike in nearly three decades.

They were out on bail when the videos were posted on Lee's blog.

In the videos, Liu and He said police officers assaulted them in a bid to extract confessions.

They also alleged they were given death threats while being interrogated. They later withdrew the allegations when they were jailed.

"Ms Lee's conduct amounted to contempt of court by creating a real risk of prejudice to the criminal proceedings which were pending then," the Attorney General's Chambers (AGC) said in a statement sent to AFP on Friday.

The statement said that the videos created a "real risk" that those involved in the case "would be improperly influenced" in assessing the confessions of He and Liu.

"All members of the public should note that contempt of court in its various forms harms the proper administration of justice in Singapore," it said.

"Left unchecked, such conduct can obstruct the determination of the truth or erode respect for our judicial institutions."

When contacted, Lee told AFP she had not read the letter as she was travelling overseas.

Separately, the AGC also warned the public and the media against issuing statements that could "improperly influence" a coroner's inquiry into the death of US scientist Shane Todd, who was found hanged in his Singapore apartment last year.

Singapore police says it is a suicide but his parents believe he was murdered because of his work involving US national security.

The proceedings ended last month, and the state coroner is expected to deliver the verdict on July 8.