Police are keeping a constant watch on an Islamic centre in Purley after right wing extremists threatened to “have the place over”.
In a YouTube clip English Volunteer Force and English Defence League (EDL) supporters try to get into Anjuman-e-Zaini in Brighton Road by pressing the intercom and rattling the doors.
After no-one answers they try the doors before announcing to the camera “This is known as an illegal mosque”.
And they say they will be back to “have the place over”.
Members of Anjuman-e-Zaini have taken the threat very seriously with the secretary Shaukat Dungarwalla calling the police as soon as he was aware of the video.
He said: “We have not taken it lightly.
“The police have been very supportive on this matter and it has gone up to Scotland Yard.
“They have put a continuous watch on the place which has reassured us.
“Anti-terrorist and CID officers are working on the issue; they have taken it as seriously as that.”
This is not the first time Anjuman-e-Zaini has been targeted as Mr Dungarwalla says people tried to burn the centre down during the riots.
He said: “They blocked our entrance and collected material and set fire to it but they weren’t successful.
“And the people who tried to set fire to our place used the wrong door and they thought it was the main door.”
Facebook posts replicated on the anti-English Defence League website EDL News show a discussion between EDL supporters about when they will strike the building.
It is not clear whether they intend the attack to be this Friday or next Friday.
One of the posts says: “We don’t want to spoil the surprise for the muzzies.”
A Croydon police spokesman said: “We are aware of this online article and we are currently liaising with the Islamic Centre on this issue.”
Anjuman-e-Zaini is an authorised place of worship.
English Volunteer Force is a splinter group of the EDL.