LONDON (Reuters) - British Prime Minister Boris Johnson said he would act to stop the early release from prison of convicted terrorists following a street attack by an Islamist militant days after he was set free half way through his jail term.

Sudesh Amman, jailed in 2018 for possession of terrorist documents and disseminating terrorist publications, was shot dead by police on Sunday after he stabbed two people with a 10-inch (25-cm) knife in a rampage on a busy London street.

Amman, 20, had previously praised the Islamic State group, shared an online al Qaeda magazine and encouraged his girlfriend to behead her parents.

Johnson said he had come “to the end of my patience” with the freeing of offenders before they had completed their sentences and without any scrutiny.

“We do think it’s time to take action to ensure that people - irrespective of the law that we’re bringing in - people in the current stream do not qualify automatically for early release,” Johnson said in a speech.

The government had already promised tougher rules on terrorism since another former convict killed two people and wounded three more before police shot him dead near London Bridge in November.

Justice minister Robert Buckland said that following Sunday’s attack, emergency legislation would be introduced to make immediate changes in dealing with people convicted of terrorism offences.

“Offenders will no longer be released early automatically and any release before the end of their sentence will be dependent on the risk assessment of the parole board,” he told parliament, adding the change would apply to serving prisoners.

Johnson said efforts to deradicalize and rehabilitate militants have had little success.

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FAKE BOMB

Amman had been released from prison on Jan. 23, according to police, having been jailed for promoting violent Islamist material.

On Sunday afternoon, he stole a knife from a shop and went on the rampage with a fake bomb strapped to his body. In an attack that lasted around 60 seconds, 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 by armed police.

Two of the three injured have been dishcharged from hospital and the third was in a serious but stable condition, police said on Monday.

In November 2018 Amman pleaded guilty to terrorism charges and the following month he was sentenced to more than three years in prison.

His mother, Haleema Faraz Khan, told Sky News he was a “nice, polite boy” who was radicalized online and in prison. She said she had spoken to her son hours before the attack, and he had seemed normal when she saw him days before.

Britain has about 220 people in prison with terrorism convictions.

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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.

Ian Acheson, who carried out a review of the management of Islamist extremists in jail, said the prison service did not have the 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 senior counter-terrorism police officer, said dozens of other people convicted of terrorism offences were due to be released early under the sentencing guidelines.

‘VIRUS’

“We have an issue about if you have about 200 or so inside, the question is how do you detain them?” Johnson said.

“Do you detain them en bloc as it were in one group and try and keep them together because that avoids them infecting or passing the virus of their beliefs to others in jails. Or do you disperse and try to stop them reinfecting each other?”

Amman was 17 and living at home with his family when he first began committing terrorism offences, according to authorities. Police said he had downloaded material about making explosives and carrying out terrorist attacks.

Messages showed that he had discussed with his family, friends and girlfriend his extreme views and desire to carry out an attack, often focused on using a knife, prosecutors said. In one, he encouraged his girlfriend to behead her parents.

Islamic State claimed responsibility for Sunday’s attack although police said it was an isolated incident.