Popular national parks in England and Wales are being used by suspected terrorists in Britain to carry out training exercise, a media report said on Monday.
A total of 20 men belonging to various groups, some of them with known terrorist links, are being monitored by the anti-terrorist branch of London's Metropolitan Police after this trend came to light, The Guardian newspaper reported, quoting unnamed security sources.
"Police believe they have clear evidence that the men were preparing for a mission of some sort," the newspaper quoted the sources as saying.
However, none of them are believed to be related to the plot to blow up US-bound airplanes, which was foiled with the arrest of 24 people on Thursday.
Investigators have collected evidence regarding the exercises in England's Lake district to be passed on to government prosecutors.
However, the exercises did not involve explosives or weapons training, the report said.