LONDON (Reuters) - Three men convicted of terrorism offences, including the brother of the Manchester Arena suicide bomber and an Iraqi who tried to blow up a London underground train, have been charged with attacking a prison officer, police said on Wednesday. Hashem Abedi, 23, whose brother Salman killed 22 people at the end of an Ariana Grande concert in 2017, and Ahmed Hassan, 21, who tried to detonate a homemade bomb on a packed commuter train later that year, are accused of assaulting a prison officer at the maximum security Belmarsh Prison in east London. A third man, Muhammed Saeed, 22, who was jailed last year after he admitted possessing articles connected to preparing for acts of terrorism, was also charged. The three have been charged with causing actual bodily harm. Abedi, born to Libyan parents who emigrated to Britain, was also charged with assault on a second prison officer during the incident which took place in May last year. All three are due to appear at Bromley Magistrates’ Court on April 7. Abedi is serving at least 55 years behind bars after being found guilty of murder last year, while Hassan was jailed for 34 years for his botched attack that injured 30 people. There has been concern about how those convicted of terrorism in prison are dealt with and the danger that they might radicalise others. In 2016, Britain announced plans to isolate radical Islamists in high security jails to limit their ability to influence other inmates amid concerns that prisons were breeding grounds for extremists. Last October, two inmates of a British jail who tried to murder a prison officer while wearing makeshift suicide-bomb belts, were convicted after an investigation by counter-terrorism police.