Six convicted terrorists have been released from prison and convicted of a further terrorist offence within seven years, it has been revealed, as parliament heads into a debate over emergency laws designed to keep extremist prisoners in jail for longer.

Between January 2013 and December 2019, 196 individuals convicted of a terrorist offence were released from prison in England and Wales with 3.06% of them going on to be convicted of a further terrorist offence.

The figures, which were released to Lord Anderson, the former independent reviewer of terrorism legislation, through a written question to the government, come as parliament is set to debate emergency legislation announced less than 24 hours after the convicted terrorist Sudesh Amman stabbed two people in south London.

The proposals, which the government hopes to rush through parliament in a single day, will block the automatic release of about 50 serving terrorist prisoners at the halfway point of their sentences.

Human rights experts have said applying a change in the conditions of a sentence retrospectively is potentially unlawful and that the figures uncovered by Anderson are further evidence of a kneejerk response by the government.

Raj Chada, a partner and human rights specialist at Hodge Jones & Allen Solicitors, said: “The rate of reoffending hardly merits the junking of basic principles of the rule of law and human rights. This is not evidenced-based policymaking, but panic-induced populism.”

The reoffending figures do not include Amman, nor Usman Khan, the convicted terrorist who killed two people in London Bridge in November, as they were shot dead, nor does it include those whose terrorist criminality is yet to be detected.

Raffaello Pantucci​, a senior associate fellow at Rusi, an independent international defence and security thinktank, said: “There is always the complicating factor of people being convicted on other charges, but even if you throw in some mitigating factors like that for the data, it does certainly suggest that just using sentence extension as an answer might not be dealing with the problem.

“These figures suggest that there are quite a few former terrorist offenders out there who have not gone back into terrorist activity, and we have not really been presented with the case that all of those who are currently inside are completely different to this previous cohort.

“There are clearly some very dangerous terrorist offenders sitting in the UK’s jails, and we need to find ways of managing them. But our response needs to be focused on them, and separate them out from those who pose less of a risk, rather than simply grouping them all together.”

The government faced immediate accusations of developing policy on the hoof and ignoring the crisis in prisons when it unveiled the emergency legislation last week.

Critics have asked for more focus to be placed on rehabilitation behind bars rather than the length of sentences.

Answering on behalf of the government, Lord Keen, the House of Lords spokesperson for the Ministry of Justice, said: “All those convicted of an offence under the Terrorism Act who have been released on probation are closely managed by the National Probation Service.

“HMPPS works closely with law enforcement partners to share information and manage the risks that these offenders present in custody and on probation to reduce the risk of reoffending, and to support them to reintegrate into the community.