Six of the eight terrorist plotters who were jailed along with London Bridge attacker Usman Khan in 2012 have also been freed from prison, it has emerged.

The nine jihadists were members of an al-Qaeda-inspired cell which plotted to blow up the London Stock Exchange and kill Boris Johnson.

One is still in prison, another was convicted for a further terror plot and Khan is dead - leaving six back on the streets, it is believed.

Three of the nine - Khan, Mohammad Shahjahan and Nazam Hussein - were initially handed indefinite prison terms, but the trio won an appeal in 2013 which changed them to fixed sentences.

Allowing their appeal, former press inquiry chair Lord Justice Leveson found they had been 'wrongly characterised' as more dangerous than the others.

Khan was released in December 2018 after serving half of his fixed sentence - and the other two have also been freed, The Sun on Sunday reported.

Members of the Al Qaeda-inspired gang who plotted to blow up the London Stock Exchange and kill Boris Johnson. From left to right, top row: Mohammed Moksudur Chowdhury, Mohammed Shahjahan, Shah Mohammed Rahman; middle row: Mohibur Rahman, Gurukanth Desai, Abdul Malik Miah. bottom row: Nazam Hussain, Usman Khan, Omar Sharif Latif

Of the others, four - Shah Mohammed Rahman, Omar Sharif Latif, Gurukanth Desai and Abdul Malik Miah - have also been released from prison.

Another plotter, Mohibur Rahman, was jailed again in 2017 for plotting a 'Lee Rigby-style' terror attack against the police or military.

That leaves Mohammed Moksudur Choudhury, who the Daily Telegraph reports is still in prison. It is unclear why, as half of his sentence would have elapsed by now.

It is also not clear when the various prisoners were released. Hussain's revised sentence was the same as Khan's, while Shahjahan - who was described at the time as the ringleader of the terror plot - received a longer sentence.

The nine men were arrested in 2010 and the time they had already served in custody was counted towards their prison sentences.

At the trial in 2012, Woolwich Crown Court heard how the nine jihadists had plotted an al-Qaeda-style attack to detonate a bomb at the London Stock Exchange.

In addition, a hand-written target list found at one of the plotters' homes also included the names and addresses of the Dean of St Paul's Cathedral, Boris Johnson who was then Mayor of London, two rabbis, and the US Embassy in London.

London Bridge terrorist: Usman Khan (pictured) carried out the atrocity on Friday a year after he was released on licence

Khan, then aged 20, was secretly recorded talking about plans to recruit UK radicals to attend a training camp in Kashmir.

His home in Stoke-on-Trent was bugged as he discussed plans for a firearms training camp, which was to be disguised as a legitimate Islamic religious school, the court heard.

Some London and Cardiff-based members of the group discussed launching a 'Mumbai-style' atrocity, while the Stoke extremists talked about setting off pipe bombs in the toilets of two pubs in their home town.

The group was also linked to radical preacher Anjem Choudary by a mobile phone seized from an address of one of the plotters.

Prosecutor Andrew Edis QC said the jihadists had 'decided that ultimately they would be responsible for very serious acts of terrorism'.

Passing sentence on February 9, 2012, Mr Justice Wilkie, said the plot was a 'serious, long-term venture in terrorism' that could also have resulted in atrocities in Britain.

Khan, Hussain and Shahjahan had had originally been handed indeterminate sentences after they admitted terrorist offences in 2012.

However, in 2013 Lord Justice Leveson wrote that the original decision had 'wrongly characterised' the trio as more dangerous than the others.

'Although we recognise that training terrorists in the use of firearms could only lead to potential loss of life... the fulfilment of that goal was further removed and there were other obstacles,' Leveson wrote.

In 2013, the Court of Appeal sentenced Shahjahan to 17 years and eight months and Khan and Hussain to 16 years, along with five-year extended licence periods.

Released: Terrorist plotters Mohammed Shahjahan (left) and Nazam Hussain (right) were initially handed indefinite jail terms which were later converted to fixed terms, like Khan

That meant Khan left prison in December 2018, apparently feigning rehabilitation, but committed the London Bridge atrocity only 12 months later.

The Parole Board said it had played no role in Khan's early release.

The terrorist 'appears to have been released automatically on license (as required by law), without ever being referred to the board,' a statement said yesterday.

The nine men sentenced in February 2012 were sentenced under law from 2003, which said people given extended sentences would be released on licence at the midway point.

This meant that Khan only had to eight years in prison, taking into account the 408 days he was behind bars before his trial.

The law covering extended sentences was changed in December 2012, but Leveson used the previous law in the appeal as it was the one used at the original sentence.

The UK head of counter-terrorism policing, Neil Basu, said he believed Khan had complied with an 'extensive list of licence conditions' following his early release.

Emergency: Police surround London Bridge terrorist Usman Khan moments before shooting him dead after he killed two people in a knife rampage on Friday

The attack has prompted the Ministry of Justice to review the licence conditions of every convicted terrorist released from prison, which is understood to be around 70 people.

Prime Minister Boris Johnson claimed that scrapping early release from prison would have stopped Khan.

Mr Johnson said: 'What I have seen over the last 24 hours has made me angry - it's absolutely clear that we can't carry on with the failed approaches of the past.'

He added: 'If you are convicted of a serious terrorist offence, there should be a mandatory minimum sentence of 14 years - and some should never be released.

'Further, for all terrorism and extremist offences the sentence announced by the judge must be the time actually served - these criminals must serve every day of their sentence, with no exceptions.

'These simple changes, in line with what I've been saying since becoming Prime Minister, would have prevented this attack.'