Three convicted terrorists allegedly attacked a prison officer so badly that he was left with hearing problems, a court has heard.
In May last year, Hashem Abedi, the brother of the Manchester Arena suicide bomber, and Ahmed Hassan, the Parsons Green bomber, allegedly attacked prison officer Paul Edwards when they were out of their cells in HMP Belmarsh.
A third accomplice, Muhammed Saeed, was also involved, Westminster magistrates heard on Wednesday.
Hassan, Abedi and Saeed are all charged with actual bodily harm, with Abedi also charged separately with assault of an emergency worker.
Saeed, who last year pleaded guilty to five counts of possessing terrorist material, told the deputy chief magistrate that he indicated a plea of not guilty to the prison assault charge.
Mel Kelemework, defending, said: "I have received instructions that Mr Saeed says he did not assault the officer."
Saeed, 23, appeared over video link from the maximum security prison, Whitemoor, in Cambridgeshire. But Hassan, 21, and Abedi, 23, refused to leave their cells to answer the charges because they believed they were appearing on Thursday, the court heard.
Nicholas Alexander, prosecuting, said: "They are unrepresented. It's quite clear the defendants have indicated they do not wish to attend. They are unwilling to leave their cells."
District Judge Tan Ikram said: "I will list this matter again at 12pm, midday, tomorrow. I will give them the benefit of the doubt that technically they were not due to attend today and that they were due to attend tomorrow. If there is ambiguity in their minds, they must appear at 12pm tomorrow. If they do not, it is highly likely that I will direct the use of force."
In 2017, Hassan's homemade bomb, hidden inside a Lidl bag, partially exploded on a London Underground train at Parsons Green, in west London, injuring 51 people. He was sentenced to life in prison with a minimum jail term of 34 years.
Abedi was jailed for 55 years for his part in the plot to set off a bomb at a 2017 concert by Ariana Grande in Manchester, which led to the deaths of 22 people, including seven children, as well as injuring hundreds people.
Saeed, who denies ABH, will next appear at Woolwich Crown Court on May 5.