ISIS claims 'soldier of Islam' carried out London terror attack outside Parliament after answering calls to 'target citizens of the coalition'

• ISIS news agency Amaq claims London attacker was 'soldier of the Islamic State' 
• Terror group said attack was response 'to calls to target citizens of the coalition'
• British-born Khalod Masood ploughed a 4x4 car through crowds at Westminster

ISIS has claimed responsibility for the Westminster attack which left four dead and dozens injured.

The terror group said a 'soldier of the Islamic State' carried out the atrocity in which British-born Khalid Masood ploughed a car through crowds near Parliament yesterday afternoon.

A statement by the ISIS news agency Amaq said: 'The perpetrator of the attacks yesterday in front of the British parliament in London is an Islamic State soldier and he carried out the operation in response to calls to target citizens of the coalition.' 

But it gave no name or other details and it was not clear whether the attacker was directly connected to the group. 

The carnage was unleashed on the same day Brussels was marking the anniversary of a wave of ISIS suicide bombings that killed 32 people.  

In a statement in the Commons today, Prime Minister Theresa May said the suspect was a British citizen who was known to the police and security services and had been investigated some years ago over violent extremism.

Mrs May said he was a 'peripheral' figure and 'was not part of the current intelligence picture'. She also told MPs there was 'no prior intelligence' of his intent.

Details of his background will raise questions over what security officials knew about the assailant and what decisions were taken when he first appeared on the radar.

Mrs May's statement came after armed police arrested eight people and raided six properties in London and Birmingham, where three people were detained in a flat thought to have been lived in by the killer. 

ISIS has frequently called on its supporters to carry out attacks against citizens of the U.S.-led coalition - of which Britain is a member - that has been targeting the group since 2014. 

The extremists have lost territory in their so-called caliphate across Iraq and Syria this year after offensives by local forces backed by a U.S.-led military coalition.

It is not the first time extremists have used vehicles to deliver mass casualty attacks.

In December, a jihadist hijacked a truck before ramming it into a crowd of revellers, killing 12 at Berlin's Christmas market.

Months earlier, on July 14, a national holiday in France, a man rammed a truck into a crowd in the Mediterranean resort of Nice, killing 86 people and wounding more than 400. He was shot dead by police before ISIS claimed responsibility.

Last year, a chilling ISIS instruction manual was published encouraging lone fanatics to usee trucks as weapons at large-scale events. 

The guide, which give insight on how to inflict the greatest destruction, was included in the latest edition of the ISIS magazine Rumiyah.

The terror group said an average truck would not arouse suspicion and could inflict more damage than a regular military fighter. Rumiyah stated that heavy, large, load-bearing trucks would be ideal - and to avoid small cars and large SUVs.

The article included a photo of a Macy's Thanksgiving Day Parade in New York with the caption: 'An excellent target', as well as listing political rallies, outdoor markets and festivals.

Last night ISIS supporters appeared to be celebrating the attack in messages shared on an unofficial 'ISIS Telegram Channel'. 

According to Ahmet Yayla, a senior research fellow at the International Centre for the Study of Violent Extremism (ICSVE), the messages were being shared on a 'credible' ISIS channel.

He shared screengrabs on his Twitter account, showing content of groups where messages included 'blessed London attack'.

One user shared pictures of the route the attacker took across Westminster Bridge and into the gates of Parliament, while another shared this website's headline of 'Terror at Westminster'.

In other apparent messages from supporters, a picture shows a mocked-up image of the Elizabeth Tower on fire. 

The message with the smoke billowing out reads: 'Soon. Our battle upon your land.

'Not started yet. Be upon you. Only waiting.' 

Rita Katz, director of SITE Intelligence Group, said the lack of media campaign from ISIS could show there was no coordination with ISIS if it was linked with the terror group. 

Similar pro-ISIS 'channels' shared blow by blow updates after the attacks in Nice, Paris and Orlando.

ISIS claim on an event can be 24 hours afterwards, and usually not until the attacker is confirmed dead, according to terror experts. 

Other ISIS chat rooms show mocked up images of fighters super imposed over the Houses of Parliament, according to a paper by the ICSVE.

The paper reveals ISIS supporters have been urged and shown how, to carry out attacks with vehicles.  

This morning, a  minute's silence was held nationwide at 9.33am, including in the Palace of Westminster and at New Scotland Yard, to commemorate the four innocent people who were killed.

The timing of the silence was chosen in honour of Pc Palmer's shoulder number - 933.

Aysha Frade was the first member of the public to be identified as a victim, with her principal at DLD College London describing her as 'highly regarded and loved'.

Forty other people were injured in the attack, with 29 treated in hospital, where seven remained in a critical condition on Thursday.

The casualties included 12 Britons, three French children, two Romanians, four South Koreans, two Greeks, and one each from Germany, Poland, Ireland, China, Italy and the United States. Three police officers were also hurt, two of them seriously.