TOKYO (AFP, REUTERS) - The trial of a man accused of stabbing to death 19 disabled people at a care home in 2016 was interrupted on Wednesday (Jan 8) after the man seemed to put something in his mouth, started struggling with court officials and lay on the floor writhing.

Satoshi Uematsu, 29, did not enter a plea before the incident on the first day of the trial.

His lawyer said Uematsu had a psychiatric disorder that made him mentally incompetent.

Uematsu is charged with killing 19 disabled people and wounding 26 people in the care centre - one of post-war Japan's worst mass killings.

Japanese media has said Uematsu, who appeared in court wearing a navy blue suit and tie, and with his hair in a long ponytail, had intended to plead not guilty.

But the court session abruptly went into recess after Uematsu made motions as if putting something in this mouth, Japanese media said, and began struggling with officials.

A Reuters witness saw him writhing on the floor and being restrained by three uniformed court officials.

Family members of the victims watched from a screened off area of the courtroom.

Uematsu reportedly said he wanted to eradicate all disabled people in the horrifying July 26 attack at the Tsukui Yamayuri-en centre in the town of Sagamihara outside Tokyo.

The 29-year-old is accused of breaking into the facility and moving room to room, searching for victims. Nineteen people were killed and 26 injured - half of them seriously.

He turned himself in at a police station, carrying bloodied knives and admitting to the attack to officers.

It emerged later that Uematsu had left his job at the home just months before the attack, and had been forcibly hospitalised after telling colleagues he intended to kill disabled people at the centre.

But he was discharged after 12 days when a doctor deemed him not a threat.

He faces six charges, including murder, and faces the death penalty if convicted on some of the counts.

'I HAD TO DO IT'

Since his arrest, Uematsu has shown no remorse and continued to espouse the views that apparently motivated the attack.

In interviews with Japan's Mainichi Shimbun daily he said those with mental disabilities "have no heart", claiming "there's no point in living" for them.

"I had to do it for the sake of society," he said of the attack.

"I don't think I'm innocent but it wasn't something punishable by death." Despite his statements, his lawyers reportedly plan to enter a plea of not guilty on Uematsu's behalf, arguing he was unable to tell right from wrong at the time of the attack because he was on drugs.

A test following his arrest reportedly showed traces of marijuana in his system.

In a recent interview with the Jiji Press agency, Uematsu said he would not deny in court having carried out the attack.

"It's depressing," he said. "It's like going there to get insulted." And he appeared to take pride in the devastating rampage "I did my best", he told Jiji.

KILLER WARNED OF ATTACK

Uematsu's self-styled mission to rid the country of people with disabilities shocked Japan, with experts and activists raising questions about whether others in the country might hold similar views.

Japan has been making efforts to increase accessibility - particularly in Tokyo ahead of this year's Paralympic Games - and activists hailed last year's election of two disabled lawmakers.

But some critics feel the country still falls short at fully integrating people with disabilities, and the government last year was forced to admit data on hiring people with disabilities had been padded to meet quotas.

Uematsu appeared to have been open about his prejudices well before the attack, even delivering a letter to the speaker of the Lower House of Parliament in which he threatened to kill hundreds of disabled people.

The letter reportedly clearly outlined a plan for night-time attacks against Tsukui Yamayuri-en and another facility.

In the rambling letter, he presented a vision of a society in which those with serious disabilities could be euthanised with the approval of family members since "handicapped people only create unhappiness".

Japan has one of the lowest rates of violent crime in the developed world, and the attack ranks among the worst ever in the country.

At the time, it was the deadliest since 1938, when a man armed with an axe, sword and rifle went on a rampage that left 30 people dead.

In 2019 an arson attack at a building belonging to the Kyoto Animation studio killed at least 36 people.

The court is expected to hand down a verdict against Uematsu on March 16.