Hezbollah-linked bomb factory in London 'kept hidden' from 2015: Report

A secret bomb factory run by members of the Iran-backed movement Hezbollah was found on the outskirts of London in 2015, with as much as three metric tonnes of bomb-making ingredients, the Daily Telegraph reported on Monday.

The case, which was kept "hidden from the public", unfolded after the British police and the MI5 intelligence service were tipped-off by a foreign government, security sources told the daily. Thousands of disposable ice packs containing three tonnes of ammonium nitrate, an ingredient common in homemade bombs, were found in the venue, according to the sources.

One man was arrested in a series of four raids in northwest London associated with the case. He was later released without charge after what the paper said was a "covert intelligence operation" that was not aimed at seeking criminal prosecution.

The paper said that the decision not to inform the public about the discovery, which came shortly after the Iran nuclear deal was concluded, would "raise eyebrows".

While the then prime minister David Cameron and home secretary Theresa May were informed of the case, MPs who were debating whether to ban Hezbollah in Britain were not.

Hezbollah's military wing was banned at the time but the Lebanese Shia group in its entirety was only added to Britain's terrorist group list earlier this year.

The paper said that similar discoveries of ice packs used to store explosives were made in other parts of the world. There were no imminent attacks and the ammonium nitrate had not been weaponised, the report added.