Terror attack: the bus which was bombed in Tavistock Square on July 7, 2005 (Picture: Getty)
The trio were held during a shop raid after IS propoganda and maps of London were found on their computers.
Documents containing threats against the Pakistan Army were also discovered, but no weapons were found.
They were identified as Azmatullah and Abdul Rehman and Muhammad Ibrahim, according to reports in Pakistan.
The group were questioned over suspicions they were plotting a terror attack in London this week after an intelligence tip-off, the Daily Mirror reported.
They were arrested at a shop in the Shamshadu Bazaar in the North West province, which borders Afghanistan, on Thursday.
Security checks on international flights from Pakistan have been stepped up since their arrest.
Former Scotland Yard terror chief Peter Clarke told the Mirror: “Every year since 7/7, massive plots to commit terrorist acts have been thwarted."
This week marks ten years since 52 people were killed by suicide bombers on London's transport network.
Prime Minister David Cameron is set to join families of the victims for a memorial event in Hyde Park on Tuesday.
Last week rough sleepers sparked outrage by camping at the 7/7 memorial and turning the plaque inscribed with the names of the 52 victims into a dinner table
This week marks ten years since 52 people were killed by suicide bombers on London's transport network.
Prime Minister David Cameron is set to join families of the victims for a memorial event in Hyde Park on Tuesday.
Last week rough sleepers sparked outrage by camping at the 7/7 memorial and turning the plaque inscribed with the names of the 52 victims into a dinner table