London's Metropolitan Police said it was investigating the hour-long film, which was posted on YouTube on Wednesday but has since been removed.
"We're aware of the video reportedly released by al-Shebab," a Scotland Yard spokesman told AFP.
"We are currently assessing its content. A number of individuals have been spoken to following the release of the video."
At least four Muslim commentators - all of whom have spoken out against extremism - said they had been visited by police after being named in the film.
The US-based monitor SITE Intelligence Group had identified the video as having been produced by the Shebab, the Somali group that claimed responsibility for a bloody attack at a Nairobi shopping mall last month.
Reportedly narrated by a man with a British accent, it singled out the commentators as having "mutilated the teachings of Islam", according to the Guardian newspaper.
Ajmal Masroor, a London-based imam and journalist, wrote on his Facebook page that police had told him "to be more vigilant".
"The basic message... was that my life was in imminent danger from the terrorists," he wrote.
He added: "I shall speak out loud and clearly against extremism and terrorism no matter how many threats I receive."
Mohammed Ansar, a filmmaker and journalist, said police were now regularly patrolling outside his home.
"In between locksmiths, security people and interviews," he wrote on his Twitter page.
"It is quite a thing to have your faith and values truly put to the test. To have your life and those you love, at risk. Quite a thing."
Commentator Mohammed Shafiq and Usama Hasan, a senior researcher for the anti-extremist think-tank Quilliam, also said they had received visits from the police.
The video was titled "The Woolwich Attack: It's an Eye for an Eye" in reference to the British soldier who was hacked to death in Woolwich, southeast London, on May 22.
Two Muslim converts are due to stand trial for the murder next month.
The video encouraged Muslims to carry out attacks on British soil, according to reports, as well as identifying 11 Britons who it said had died fighting for the Shebab.
COMMENTS (15)
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It is stupid to raise Kashmir as a reason for Somali terrorists to threaten UK Muslims.
@Amir: " It’s the Saudi wahabists and gulf supporters. They are the one who are responsible for the terrorism around the world. No doubt American/Indian policies contribute towards it but terrorists have been targeting civilians in Iraq/Afghanistan/Pakistan/Libya/Syria thanks to the jihadist ideology funded by gulf."
You feel that the Saudi fund and Wahhabi, Indian policies and Americans are responsible for terrorism. Blame all others . Have you ever thought why the person carrying out the terrorist activities fall for the Saudis, so called India , Jewish or american policies. Are they not responsible. What an easy method to clear your conscience! others are responsible and we are the victims of the others policies.which you perceive as bad, while others may have a different opinion. Such mindset will never be able to overcome the extremism. You are also a fodder for this extremism. Try to make an introspection .
Say whatever you like, the fact of the matter is that, YOU, the followers and votaries of Islam, have lost any moral high ground you may have once had. Threats, coercion, murder on a scale not seen since the Holocaust, mayhem, destruction..... these things are the legacy of Islam! One day, Muslims, you will be repaid in kind.
@LaLakiMKaa
Kashmir is only a very small part of the big problem. Real issue is the constant flow of funds that these terrorists have. Who is the provider of this funding? It's the Saudi wahabists and gulf supporters. They are the one who are responsible for the terrorism around the world. No doubt American/Indian policies contribute towards it but terrorists have been targeting civilians in Iraq/Afghanistan/Pakistan/Libya/Syria thanks to the jihadist ideology funded by gulf.
Education is the key . Please start education people of all religions all over the world. I mean make it compulsory. Low self esteem is one reason they people turn terrorists - It gives them a so - called anchor , a platform to feel 'wanted' . Give them education, jobs and they will be busy .
@LaLakiMKaa: You thinking inside the small very tiny box...like they saying goes think outside the box....when there is injustice there is no peace, in other words there is no salam...another word for peace...when Muslims don't follow Islamic code of conduct in their personal life...they are unjust...when majority does not follow a righteous code of conduct their become unjust nations and chaos erupts, when you are unjust you are in a hole....like we see in muslim countries today. Islam is justice...when Islam prevails so does peace and harmony....70 years ago it was not like this ....all this started with moral decay of Islamic values in muslim countries became a norm, we cannot blame anyone...as we are following our desires...putting a rubber stamp of Islam on it and its in reality its just the evil opposite of Islam.
The "quillium" group are the same people who feted the ex edl members - they themselves are ex jihadists now turned anti extermist think tank! The authorities should investigate who is behind this organisation and who is financing this "think tank".The lib- labs should also investigate one of this "quillams" member is this prospective candidate.Think -tank-what a laugh!
@LaLakiMKaa: if you learn to earn there will no terrorism in world,
one who has taken the oath of citizenship has taken oath of loyalty to that land, and breaking any oath, or going against an agreement is against Islam...so again in this example, the people claiming to be on the right path, are not.
No sane voices will be allowed !
If any one has mutilated the teachings of Islam, it is these murderers.They carry a perverted version of Islam in their brains,and use it for destruction and killing.
I think all this is happening because of kashmir issue...If India solves the kashmir issue there will be no terrorism in the world...sone by pakistanis and muslims people..If Israel solves palestein there will be no terrorism..........But I think if there is no terrorism then how will muslim countries survive in the name of peaceful $%&
This threat is over and above the threats by the their border security agency.