The British government promised sweeping changes to the system for dealing with convicted terrorists released from prison after a man stabbed two people in a busy south London street on Sunday.

Police officers are seen near the site where a man was shot by armed officers in Streatham, south London, Britain. February 3, 2020.
Police officers are seen near the site where a man was shot by armed officers in Streatham, south London, Britain. February 3, 2020. (Reuters)

British Prime Minister Boris Johnson will set out tougher rules on releasing people convicted of terrorism offences after an attacker injured two people in a stabbing spree days after he was set free halfway through his prison term.

Sudesh Amman, jailed in 2018 for possession of terrorist documents and disseminating terrorist publications, was shot dead by police on Sunday after he went on the rampage with a stolen 25 cm knife on a busy London street.

Amman had previously praised the Daesh group, shared an online al Qaeda magazine and encouraged his girlfriend to behead her parents.

Johnson said the government would announce fundamental changes in dealing with people convicted of terrorism offences.

"Those measures will build upon the actions we have already put in place," interior minister Priti Patel said.

She said there would be legislation to end the early release from prison of counter-terrorism offenders.

"It is right that these individuals are kept behind bars," Patel said.

British politicians have repeatedly discussed tougher rules on terrorism, calls that increased after a former convict killed two people and wounded three more before police shot him dead near London Bridge in November.

Johnson said that since that attack, the government had "moved quickly to introduce a package of measures to strengthen every element of our response to terrorism – including longer prison sentences and more money for the police".

Sunday in Streatham 

Sunday's attacker, Amman, had recently been released from prison, according to police, having been jailed for promoting violent material.

He went on the rampage at around 1400 GMT on Streatham High Road, having strapped a fake bomb to his body. He stabbed two people, while a third suffered minor injuries caused by shattered glass when police opened fire.

Amman was under surveillance at the time of the attack by armed police, who shot him dead.

In November 2018, he pleaded guilty to possessing terrorist documents and disseminating terrorist publications, and the following month he was sentenced to more than three years in prison.

Ian Acheson, who carried out a review of the management of militants in jail, said the prison service did not have the appetite or aptitude to manage terrorist offenders.

"We may need to accept there are certain people who are so dangerous they must be kept in prison indefinitely," he told BBC radio.

Mark Rowley, formerly Britain's most senior counter-terrorism police officer who was in post when Amman was arrested, said dozens of other people convicted of terrorism offences were due to be released soon.

Amman was 17 and living at home with his mother and younger siblings when he first began committing terrorism offences, according to authorities. 

Police became aware of his activities in April 2018 and he was arrested by armed officers in a north London street a month later.

When officers examined his computers and phone, they found he had downloaded material about making explosives and carrying out terrorist attacks, according to prosecutors.

Messages showed that he had discussed with his family, friends, and girlfriend his violent views and desire to carry out an attack, often focused on using a knife, prosecutors said.

In December 2017, Amman posted a picture of Daesh leader Abu Bakr al Baghdadi, who was killed in a US raid in Syria in October, and told his brother in a message that "the Islamic State [Daesh] is here to stay".

Police said he had shared an online al Qaeda magazine with his family and while in a discussion about school with a sibling he wrote he would "rather blow myself up". 

Source: Reuters