Three would-be suicide bombers have been convicted of plotting to carry out terror attacks in the UK which would have been more deadly than the 7/7 bombings in 2005.

The men were key figures in a Birmingham-based terror cell which planned to detonate eight to 10 suicide bombs and timed explosive devices that prosecutors said could have caused "death and injury on a massive scale". They are among a number of extremists in the UK who have been radicalised by the magazine Inspire, a self-help guide produced by al-Qaida in the Arabian Peninsula (AQAP) which is pushed on internet forums to would-be terrorists.

They duped members of the public into donating thousands of pounds to fund their terror plot by posing as collectors for the charity Muslim Aid in Sparkhill, Birmingham. Within two weeks they were able to raise £14,500, which they diverted to fund their activities.

Mr Justice Henriques told the trio it was clear they were planning to carry out a spectacular bombing campaign to create an anniversary along the lines of 7/7 or 9/11 and that they would all face life in prison when they are sentenced in April or May.

The ringleaders, chemistry graduate Irfan Naseer, 31, and Irfan Khalid, 27, both from Sparkhill, Birmingham, had travelled to Pakistan twice for training – on the second occasion spending two months at an al-Qaida training facility in Miran Shah, in north Waziristan, where they had to flee from American drone strikes.

When they returned to Birmingham in the summer of 2011 they shared their knowledge with Ashik Ali, 27, of Balsall Heath in the city. He rented a council flat which became a makeshift bomb factory and the hub of the terror plot. In the flat the trio experimented with making bombs using ammonium nitrate extracted from sports injury cold packs via a recipe which experts told the court could have created a viable device.

Speaking to Naseer, the judge said he had been convicted on "overwhelming evidence" and that he would face "a very long minimum term". He said: "You are a highly skilled bomb maker and explosives expert. Your mindset was similarly manifest.

"You sought to persuade others that a terror plot here in this country was by far preferable to fighting jihad abroad.

"The scale and extent of your ambition was similarly manifest. You were seeking to recruit a team of somewhere between six and eight suicide bombers to carry out a spectacular bombing campaign, one which would create an anniversary along the lines of 7/7 or 9/11.

"It's clear that you were planning a terrorist outrage in Birmingham."

The judge told Khalid he was "virtually inseparable" from Naseer. "You were very much his confidant and his right-hand man."

He said to Ali: "I had mistakenly formed the view that you were a rather foolish recruit to this terrorist cell and rather less dangerous than your co-accused. You have dissuaded me from that view. You are intelligent, devious and highly manipulative."

Marcus Beale, assistant commissioner of West Midlands police, who worked with the security services to intercept the plot, said: "They wanted to commit their own 9/11. They were critical of the 7 July bombers because they didn't kill enough people. From the evidence we presented to the court there were 8-10 bombs that they wanted to deploy, a mixture of suicide bombs and IEDs [improvised explosive devices]. So in terms of their capability, if they delivered on the plans that they had they would have committed mass murder on a horrendous scale."

Karen Jones, from the Crown Prosecution Service, said: "These men had dangerous aspirations and, whilst the precise targets remained unclear, the potential for damage and loss of life from their plot should not be under-estimated.

"The evidence we put to the court showed the defendants discussing with awe and admiration the attacks of 9/11 and 7/7. These terrorists wanted to do something bigger, speaking of how 7/7 had 'gone a bit wrong'.

"Having travelled to Pakistan for expert training and preparation, Naseer and Khalid returned to the UK, where they discussed attacks involving up to eight rucksacks. Had they not been stopped, the consequences would have been catastrophic."

The trio recruited others to their cause, and sent four young men from Sparkhill to Pakistan for training in 2011. But they were being watched by the police and security services, who overheard them describe the plan as "another 9/11". Officers moved in to arrest the men after they overheard them attempting to make a bomb in their council flat.

At one point the three men were heard via a bug planted in their car, mimicking Formula One commentator Murray Walker, and joking: "It's the four suicide bombers driving around ready to take on England."

Khalid also said of the plot: "This is going to kick them all, the kufar [infidels] that go to the pub and that; they have hit us in our own country, my God they hit us."

Naseer, Khalid and Ali were convicted by a jury at Woolwich crown court of engaging in conduct in preparation of terrorist attacks. Naseer was found guilty of five counts, Khalid of four and Ali of three counts – all between Christmas Day 2010 and 19 September 2011.

However, there was evidence that the men were struggling to get the ingredients for their plot and no targets were ever identified by the police or security services.

When arrested they were found in possession of just one sports cold pack kit which did not contain ammonium nitrate because the substance is no longer used in the products.

The trio were heavily influenced by Anwar al-Awlaki, the Yemen-based cleric who was a leader of AQAP until he was killed by a US drone in September 2011. He spread his extremist message through the English language Inspire magazine, which contained bomb-making recipes and encouraged individuals to radicalise themselves and carry out attacks in their own countries. A search of Ali's house after his arrest uncovered a vast library of lectures by Awlaki.

One of the plans discussed by the trio – of attaching blades to the wheels of cars in order to mow down pedestrians – came directly from Inspire, the second edition of which describes how to create "the ultimate mowing machine".

Sue Hemming, head of special crime and counter-terrorism in the CPS said the influence of Awlaki reflected a trend in cases being brought to court in England and Wales.

"Most recently, a considerable number of investigations have uncovered connection to and support for the teachings of Anwar al-Awlaki who advocated violence against the west through speeches and a publication called Inspire.

"He of course is no longer with us but his pernicious and hateful views unfortunately live on in his recorded speeches and Inspire magazine."

The three men denied all the charges against them. A total of 11 men and one woman have been charged in conncection with the plot. Four men whom the trio recruited and sent to Pakistan for training have pleaded guilty to preparation of terrorist acts. Two other members of the cell, including fundraiser Rahin Ahmed, have pleaded guilty to their role in the plot. All will be sentenced at a later date.

Two men and a woman face trial charged in connection with the plot.