A TEENAGE boy suspected of being the ring-leader in a plot to use automatic weapons and bomb-making chemicals to stage a horror terror attack in Britain is being questioned by police.

Police fear the 19-year-old and his 20-year-old brother, who has since been released on bail, were planning a copycat suicide mission like those seen in Paris in November last year.

3 The Met's elite armed unit which is on anti-terror duty 24/7 Credit: PA:Press Association

The brothers were arrested in a dawn raid on Thursday after the Metropolitan Police's Counter Terrorism Command and the South East Counter Terrorism Unit swarmed on a west London address.

The 20-year-old, who was arrested on suspicion of funding terrorism and failure to disclose information regarding an act of terrorism as well as on suspicion of preparing acts of terrorism, has now been released on bail until early November.

The 19-year-old remains in custody on suspicion of preparing terrorist acts, a Scotland Yard spokesman said.

It is understood that the plots have been linked to Islamic extremism but police have refused to give further details.

It is now feared that the brothers were not "lone wolves" but were instead involved with other forces after having been inspired by violent online Islamist material.

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In a separate matter, a third man, also 19-years-old, was arrested in south-east London on Thursday on suspicion of a religiously aggravated offence, in a separate matter.

He has since been named as Ali Esayed and was released on bail until mid October.

He had been arrested at the three-storey home in Kennington, South-East London, that he lived in with his parents and sisters.

Neighbours have now said the 19-year-old had recently begun wearing traditional Islamic clothing.

Scotland Yard has now revealed they are still searching homes across London and the Thames Valley as they continue their investigation into the suspected terror plot being formulated by the brothers.

3 Ali Esayed, 19, was arrested on suspicion of religiously aggravated offences and has been bailed until October

3 The operation is understood to be “significant” and is linked to Islamic extremism Credit: PA:Press Association

The arrests come after the commissioner of the Metropolitan Police warned a terror attack in the UK was a matter of "when, not if".

Authorities have become increasingly alert of potential terror threats with recent plots in France.

Security chiefs suspect the brothers were inspired by ISIS in Syria and are investigating if they were in direct contact. No specific target has emerged but MI5 fear they were plotting to build a bomb like those used to kill 52 people on public transport in the capital on July 7, 2005.

The terrorists involved in the 2005 attack had stockpiled hydrogen peroxide bought over the counter.

Sources said the alleged plan has been under way for weeks.

Security services have been “extremely busy” on the investigation and a similar one in Birmingham involving chemicals for a bomb.

Sources stressed the two alleged plots are not thought to be linked at this stage.

Investigations are continuing.

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