ISIS have reportedly said this morning's terror attack has 'demonstrated a weakness' in UK security.

Axar.az reports citing Daily Mail.

The Islamic terror group's supporters are 'rejoicing' after hearing news of an explosion on a London Underground train at Parsons Green station, according to SITE Intel Group.

The intelligence organisation, which has access to terrorist correspondence, tweeted: 'As #ISIS supporters celebrate news on #LondonExplosion, one remarked that the incident demonstrates "weakness" in UK security.'

ISIS have not claimed responsibility for the attack in which a crudely made bomb shot a 'wall of fire' through a District Line carriage, injuring at least 18 people.

Terrified passengers 'ran for their lives' and were seen covered in blood with scorched hands, legs, faces and hair after the incident in west London at 8.20am.

Photographs show what experts believe is a 'pretty unsophisticated' bomb in a flaming white bucket inside a Lidl freezer bag with Christmas lights protruding out of the top - a type of fuse encouraged by ISIS in its online manuals and magazines.

Security sources have said the IED had a timer, indicating the bucket bomber left in on the train and fled before it exploded.

There is currently a manhunt underway to find the attacker and it is not yet known if there is a second bomb.

Prime Minister Theresa May is to chair a meeting of the Government's Cobra emergencies committee this afternoon to discuss the incident - the fifth major British terror attack this year.