This is the terrifying moment a jealous boyfriend jumped over the counter at a minicab office and stabbed his love rival to death while chanting verses from the Koran.

Gulam Chowdhury, 24, was today sentenced to 28 years in prison after he murdered Mohammed Yasser Afzal in a frenzied knife attack at his workplace in Stratford, east London.

Dramatic CCTV footage showed a masked Chowdhury storm the E20 minicab company in the Broadway on March 24 last year before vaulting over the counter armed with a carving knife.

Brutal: Gulam Chowdhury, 24, was today sentenced to 28 years in prison after he murdered Mohammed Yasser Afzal in a frenzied knife attack at the cab office where he worked in Stratford, east London

He brutally stabbed Mr Afzal 20 times with an eight inch knife and the 22-year-old never regained consciousness.

Judge Timothy Pontius said that the footage was the worst he had ever seen.

The court heard that Mr Afzal had been in a long-term relationship with Nargis Riaz, 22, who was also seeing Chowdhury at the same time but had not told her strict parents about either boyfriend.

Ms Riaz had told Chowdhury she was terrified Mr Afzal would show intimate photographs of her he had on his mobile phone to her father - a strict Imam - and expose their relationship to her family.

Chowdhury believed it was his duty as a Muslim to defend his girlfriend's honour and hatched the plot to murder Mr Afzal, the Old Bailey was told.

Detectives investigating the murder found a series of texts from Chowdhury to her in the weeks leading up to the attack.

In one message, Chowdhury repeatedly asked Ms Riaz if she wanted his rival dead and told her: 'No one hurts Nargis and lives'.

Convicted: Chowdhury (left) and Mr Afzal (right) were both dating Nargis Riaz, 22. She told Chowdhury she was worried Mr Afzal would show her parents intimate pictures of her and he hatched the plot to kill him

Having converted to a strict form of Islam while held in an immigration detention centre, Chowdhury regularly quoted the Koran in his messages to Ms Riaz, who worked at Primark in Hackney.

He told her: 'I'm going to sort this out and sort it proper, I will use the flame from my ancestors to burn the world of this scum.'

He also wrote in another message that his ancestors were 'fearless lions that would kill for honour'.

Chowdhury claimed killing was justified by Islam and included a passage from the Koran which said: 'Cut the neck of the man who eyed up his wife'.

In another text he wrote: 'I need to kill someone'.

Chowdhury told Ms Riaz, a second year law student at City University, the attack was justified in Islam claiming: 'Cut the neck of the man who eyed up his wife.'

Later he reassured her: 'Don't worry little angel, it's me who's a psycho not you.'

Prosecutor Sandip Patel QC said Ms Riaz was treated 'like a Queen' by Mr Afzal, but had threatened to show intimate pictures to her parents during a 'difficult phase' in their relationship.

'They had known each other before and had been boyfriend and girlfriend in the past but Mr Afzal was unaware Miss Riaz was at that time seeing Mr Chowdhury,' he said.

Ms Riaz, who is also accused of murder, claimed she did not believe Chowdhury would carry out his threats.

Devious: Chowdhury was captured on CCTV as he walked into the E20 cab office on Broadway in Stratford

Armed: His face is covered with a mask and he wore dark clothing before pulling out a huge carving knife

Attack: He vaulted over the taxi office counter and launched into a frenzied attack on Mr Afzal while chanting verses from the Koran

She faces a retrial on June 8 after a jury failed to reach a verdict after 21 hours and 37 minutes' deliberation.

Chowdhury, from Barking, east London, denied, but was convicted of murder at the Old Bailey on April 22.

He was held at Broadmoor secure hospital prior to the trial, and was initially deemed unfit to plead due to mental health problems.

Sporting a straggly beard and unkempt hair, Chowdhury showed no emotion today as the judge handed him a life sentence with a minimum term of 28 years for what he described as a 'horrific' crime.

Members of the victim's extended family hurled abuse at the murderer from the public gallery as he was taken down to the cells.

In a witness statement, his father Mohammed Chowdhury paid a moving tribute to his son.

'I make this statement in relation to my beloved son who was taken from us in such a cruel and unforgiving way that we as a family to this day cannot comprehend,' he said.

'It has been just over a year since that horrendous night when my whole life changed when my son was murdered.'

He continued: 'Life will never, ever be the same. With regards the family business, we as a family cannot bring ourselves to work in the office where Yasser died.

'No dad should ever have to see their son buried. I fully expected to see Yasser married, happy and with children, but this will never happen now.'

Mr Chowdhury said he could never forgive those responsible for the death of his son, adding: 'I cannot understand why they did this to my son.'

Love rival: Chowdhury believed it was his duty as a Muslim to defend his girlfriend's honour and hatched the plot to murder Mr Afzal. The court heard she waited outside while the attack happened

Shocking: Chowdhury's girlfriend Riaz is also accused of murder, although she denies it, saying she did not believe he would carry out the attack

Frenzied: Chowdhury was sentenced to 28 years in prison after Judge Pontius described the footage as the worst he had ever seen

Sentencing, Judge Pontius said: 'A planned attack of that gravity leads inescapably to the conclusion that the intention was not to cause serious injury, but to kill Yasser Afzal.

'The evidence and in particular the plans which the defendant had clearly long formed in his mind and revealed in the many text messages to Nargis Riaz demonstrate the determination to kill Yasser Afzal.

'Further evidence shows that he had plainly determined to go to the minicab office on the evening of 24 March having made a number of previous visits to the minicab office.

'He armed himself with a large knife, he had of course during the earlier part of that evening learned from Nargis Riaz he would be alone in his office.'

The judge said he was determined in his resolve, adding: 'Probably in pursuit of a warped desire to serve the woman he loved, a resolve to cold-heartedly carry out murder.'

Detective Inspector Euan McKeeve, of the Homicide and Major Crime Command, who led the investigation, said: 'Gulam Chowdhury carried out a ferocious assault on Mohammed Afzal. The level of violence used was shocking and ensured that Mohammed would not survive the attack.