- Abdelhamid Abaaoud, 28, believed to have entered UK via Kent
- Counter terrorist forces think he had a fake passport and visited London
- Investigation launched into how he was able to move around freely
- Abaaoud killed in police raid in Paris days after horrific attacks
The mastermind behind the Paris terror attacks is believed to have visited the UK using a forged passport to seek logistical support from extremists in Britain weeks before carrying out the atrocity which killed 130 people.
It is understood Abdelhamid Abaaoud, 28, met fanatics in Britain last summer and travelled to London as part of his preparations for the horrific actions in the French capital.
The terrorist was killed in a police raid days after the Paris tragedy and is thought to have only been in the UK for a short time.
Counter terrorism forces believe Abdelhamid Abaaoud, 28, pictured, entered the UK with a fake passport
Counter-terrorism agencies say they are convinced Abaaoud slipped into the country undetected and are investigating whether he arrived via Kent.
The current theory is he used a false passport to leave no trace of his arrival or departure through UK immigration services.
It has led to a major investigation in Europe and the US to determine how he was able to move freely despite his status as a wanted man.
As previously reported, Abaaoud had pictures of reported 'targets' in Birmingham on his phone, raising fears he was plotting similar attacks in the UK.
He and Paris suicide bomber Brahim Abdeslam also made phone calls to numbers belonging to Moroccan nations living in Birmingham.
PARIS MASTERMIND WAS BEHIND OTHER EUROPEAN ATTACKS
A counter terrorism source told The Sun: 'We believe those calls were made to discuss some aspect of logistics and finances with regards to the Paris attacks.
We also think money and false or doctored documents swapped hands between Abaaoud and Brahim and their associates in Birmingham.
'Forensic evidence suggests some of the forged documents found on Paris attackers were personally handed over to Brahim and Abaaoud during visits to the UK.'
A Mail on Sunday investigation discovered the notorious jihadi, who had been linked to four foiled plots this year alone, was in regular contact with a 'network of associates' in the Midlands in the weeks before the Paris strikes, insiders believe.
Born in Belgium, Abaaoud left his home in 2013 for Syria where he trained alongside fellow extremists.
He returned to Belgium to organise a plot to kill police officers, but managed to escape when it was foiled last January.
A manhunt was launched but he evaded authorities and returned to Syria, and claimed to have made it past a Belgian border officer after he failed to recognise him from his mugshot.
He was later sentenced to 20 years in prison in his absence by a Belgian court.
According to the De Standaard newspaper, Abaaoud is also mentioned in files relating to Brahim Abdeslam for alleged crimes carried out in Brussels in 2010 and 2011.
Abaaoud even featured in an online ISIS terror magazine Dabiq featuring his life as a Jihadi.
According to the interview, he traveled to Syria 'to terrorise the crusaders waging war against the Muslims'.
He said: 'Belgium is a member of the crusader coalition attacking the Muslims of Iraq and Sham (Syria).
Abaaoud claimed that in the past he returned to Belgium to set up a safe house to plan further raids across Europe.
He said his plot failed: 'The kuffar raided the pace with more than 150 soldiers from both French and Belgian special forces units.'
He said both of his men were killed in the shootout.
He claimed it was after this, he returned to Syria due to the attentions of European security agencies.
French police have said Abaaoud planned the attack from his base in Syria with help in Belgium and France.
Abaaoud, who has regularly posed with bodies he decapitated and was seen in Greece in January but evaded arrest, was also linked to the thwarted high speed train attack earlier this year and church attacks around Paris.