A high court has refused to allow the SAR's first national security defendant, Tong Ying-kit, to postpone his hearing so he can file a judicial review to challenge the lack of a jury trial for his case.

The defense also told the court that it faced difficulty in finding an academic as an expert witness to explain the meaning of the slogan "Liberate Hong Kong, revolution of the times" when applying to have the hearing adjourned to a later date.

Tong, 24, pleads not guilty to inciting secession and engaging in terrorist activities after allegedly riding a motorbike into a group of police officers while flying a flag with the protest slogan on July 1.

He has been remanded in custody pending a 15-day trial to start on June 23. The case will be heard by national security judges Anthea Pang Po-kam, Esther Toh Lye-ping and Wilson Chan Ka-shun -without a jury.

At yesterday's hearing, senior counsel Lawrence Lok Ying-kam, for Tong, said his client has received legal aid to file a judicial review to challenge the lack of a jury trial.

The judicial review will be handled by senior counsel Philip Dykes, Lok said, adding that he hoped the case could be heard after there is a result for the judicial review.

Lok also said the trial date clashes with his working schedule on other cases, while other senior counsels who could argue the case in both English and Chinese are not available, asking the court to reschedule the trial.

He also said the prosecution has found the associate vice-president of academic affairs and external relations of Lingnan University, Lau Chi-pang, as an expert witness.

The history professor would conduct research on the slogan "Liberate Hong Kong, revolution of the times" and compile an expert report.

However, the defense has yet to find other history professors to provide an expert report for the court. Lok also said experts would need around five months to complete the report and the defense would need more time.

But the judges rejected his request, with Pang saying the national security law stated that crimes endangering national security need to be handled "in a fair and timely manner."

If the trial was postponed after the judicial review, it might not be handled in time, Pang said.

The judges also said the defense already knew in February that the trial was scheduled for June 23, and they should have enough time to find another senior counsel to represent Tong.

Toh said there should be enough time for the defense to find an academic as the trial is still two months away.

But Lok said it would not be easy to find an expert defense witness in the current political environment.

Tong Ying-kit wields a flag emblazoned with the offending slogan just before he is alleged to have run his motorcycle into a group of police officers.

Judges reject bid to delay security trial