Iran-backed extremists were caught stockpiling tons of explosive materials on the outskirts of London in a secret British bomb factory, The Telegraph revealed on Monday. The radicals linked to Lebanon’s “Hezbollah stashed thousands of disposable ice packs containing ammonium nitrate - a common ingredient in homemade bombs,” it said. The plot was uncovered by MI5 and the Metropolitan Police in 2015, said the report. According to The Telegraph, three metric tons of ammonium nitrate was discovered. Acting on a tip from a foreign intelligence agency, MI5 and the Metropolitan Police raided four properties in North West London, discovering thousands of disposable ice packs containing ammonium nitrate, the Telegraph said. A man in his forties was arrested on suspicion of plotting terrorism, but was eventually released without charges, the paper quoted “well placed sources” as saying. According to the report, the plot was part of a wider Hezbollah plan to lay the groundwork for future attacks.