LONDON - Clad in mud-smeared combat fatigues, the young Muslims trained on picturesque British farmland, hurling imaginary grenades, wielding sticks as mock rifles and chopping watermelons in simulated beheadings.
A four-year inquiry, which came to a close Tuesday with guilty pleas from the last two of seven gang members, has exposed a network of alleged British terrorism training camps meant to prepare recruits for mass murder.
Security officials believe hundreds of men -- including a gang that made a failed attempt to bomb London's transit network -- passed through camps set up across the English countryside.
Investigators say it was a worrying discovery at the heart of Britain's homegrown terrorism: training camps once thought to be exclusive to northern Pakistan or Afghanistan are being held in sleepy rural England.
The two ringleaders -- one who claimed to be the "No. 1 al Qaeda in Europe" and the other who nicknamed himself "Osama bin London -- will be sentenced next month on charges of running the camps and inciting participants to murder. Five others were each sentenced Tuesday to at least 3 1/2 years in prison on charges of attending terrorism training.
Their convictions -- two Tuesday, one last year and the rest last week following a four-month trial -- could be reported for the first time Tuesday after a judge lifted restrictions banning publication of details of the case.
Prosecutors told a court hearing that the men set up camps in idyllic spots across England to train in military skills.
National parks in the Lake District of northern England, the New Forest in the south and quiet corners of the southern counties of Berkshire, Kent and East Sussex were all used for training, including a former school.
"This was not innocent activity taking place on a camping weekend," said Peter Clarke, Britain's most senior conterterrorism detective.
Officials fear the case shows that British Muslims can be radicalized, trained and funded to carry out terror attacks -- without ever leaving the country.
The British camps also offer a glimpse of the training centers that British-based Islamic extremists allegedly hoped to open in Oregon before authorities upended the plot.
"People have got to be alert to the fact that right in the middle of our society these things are going on," said Patrick Mercer, a former intelligence officer who is a member of Parliament with the opposition Conservative Party.
The camps may help explain why Jonathan Evans, head of the domestic intelligence agency MI5, has said Britain faces an ever growing threat from about 2,000 potential terrorists within its borders.
Video secretly made at the camps showed recruits marching with backpacks -- like those used by London's transit network attackers to carry their deadly suicide bombs in 2005 -- and conducting weapons drills used by insurgents in Iraq and the Taliban in Afghanistan.
An undercover police officer, code-named "Dawood," infiltrated one group and captured cell phone video of the training. One clip showed trainees rehearsing a beheading with a watermelon.
The gang of North African men who made a failed attempt to bomb London's transit network on July 21, 2005 -- two weeks after the July 7 subway and bus strikes that killed 52 commuters -- met and were trained at one of the camps, said a government security official, who agreed to discuss the inquiry only on condition of not being quoted by name.
Another recruit, Hussan Mutegombwa, was ordered jailed for 10 years in November over an alleged plan to carry out a suicide bombing in Somalia, police said.
Officials said the ringleaders of the camps were two London-based preachers -- Atilla Ahmet, who once said in a CNN interview that he was "the No. 1 al Qaeda in Europe," and Mohammed Hamid, who gave himself the nickname "Osama bin London."
Ahmet is a longtime aide to radical cleric Abu Hamza al-Masri, an Egyptian the U.S. is attempting to extradite over the alleged plan to set up terrorist training camps in Oregon.
Hamid, originally from Tanzania, hand-picked recruits from mainstream mosques, inviting them for radical meetings at his home and then selecting a smaller number to attend the camps, police said.
Prosecutors said Hamid was candid about his hope that recruits could dwarf the scale of the 2005 London bombings. He hoped they would carry out six or seven major attacks before London hosted the 2012 Olympics, prosecutors said.
"Fifty-two. That's not even breakfast for me," Hamid said, referring to the number killed in the 2005 bombings, in a recording from a secret bug installed in his home which was played at his trial.
Dozens trained at Hamid's camps were hoping to carry out attacks, said a senior police official, who insisted on anonymity to discuss counterterrorism work. "There was repeated talk of finding and killing nonbelievers," he said.