Metropolitan Police is warning service station owners in the Capital to prepare for potential mob violence focused on forecourts over the Halloween weekend.

Last year at Halloween large groups of motorcyclists swooped on forecourts stealing petrol and goods from their shops and in one case a fire extinguisher was thrown through a window.

Inspector Rob Webb said there was currently no intelligence to say there would be similar disorder, but Metropolitan Police was preparing a major operation in case of a repetition.

He warned: “The key sector identified as potentially most vulnerable to their activity is petrol retail.”

He added: “There is nothing at this time to suggest that any specific criminal activity is planned but because of the way the group operates we may not be aware of its activity until much nearer Halloween.

“One of our key tactics is to forewarn those who may be vulnerable offering suggestions on keeping their business and staff safe and secure. The intention is not to be prescriptive or interfere in their retail operations, but to offer choices and suggest measures that reduce the likelihood of theft and damage.”

Last year the groups gathered in Thamesmead, Bexley and Croydon and incidents were restricted to south London, but he said forecourts across the Capital could be vulnerable. Halloween this year is on a Monday so groups may gather during the preceding weekend.

Metropolitan Police has already contacted some groups operating forecourts in itsarea and will be keeping forecourts updated through social media.

It is advising that usual security procedures should be followed such as insisting motorcyclists remove their helmets and that number plates are visible before authorising fueling, and ensuring CCTV is working well.

Any loose non-essential equipment on the forecourt, such a marketing material, should also be removed so there are fewer items that can be thrown.

Anyone who hears any information about motorcyclists planning to gather over Halloween, or who wants advice on security over Halloween, should contact Inspector Webb at 020 8733 3268 or Robert.Webb3@met.police.uk