A 19-year-old man has been arrested after a suspicious device was blown up in a controlled explosion in London

A ‘viable device’ found on a London Underground train was part of a plot to attack the transport network, it is believed.

A 19-year-old man was Tasered and arrested under the Terrorism Act today after a suspicious package was exploded on a train.

The teenager was detained at 12.20pm in Holloway, North London, one day after the item was detonated in a controlled explosion at North Greenwich station.

And the Ministry Of Defence told its staff in a memo that the culprit could have planted more devices, according to The Telegraph.

It said: ‘This increase is in response to the discovery of a suspected viable improvised explosive device (IED) on a London Underground train yesterday.

‘It is unknown who placed the device and what their motivation was. Therefore it remains possible that the perpetrator may attempt to place further devices. The threat level will continue to be reviewed as further information is received.’

Witnesses described how officers shouted ‘armed police, don’t struggle´ as they arrested the white bearded man wearing a hoodie, jacket, jeans and trainers.

Security has been ramped up on London’s public transport network since with more officers, including armed police, on patrol at travel hubs and high visibility patrols.

Yesterday, passengers were evacuated from the station near The O2 Arena in East London as alarm bells rang and a huge section of the Jubilee line was suspended.

Shortly after 11am, travellers were told to leave the station which was closed for more than seven hours while the item was made safe underground.