Police fear that a man at the centre of a three-day stand-off with armed police in London may have stockpiled petrol inside his home.

The Metropolitan Police said officers on the scene are concerned that a man holed up in a property on Wood End Lane, Northolt, may have stockpiled "petrol and combustible material".

The siege began in the early hours of Friday, 21 October, with armed officers concerned about the man's mental health. A 200m cordon is in place, and 80 residents have been forced out of their houses– some spending two nights away from home.

The man is believed to be in his 40s and owns up to four Rottweiler dogs, according to reports. The presence of the dogs is believed to be one reason why police are taking a cautious approach to apprehending the man.

But with no signs of the siege ending, police say they are "treating seriously" reports that the man has "quantities of petrol and combustible material" inside his home, according to the BBC.

The Met Police force added that the man has "not engaged at all" with them and any attempt to access the home "may make his behaviour unpredictable".

Ch Supt Paul Martin said: "Our aim is to bring this to a safe conclusion for everyone. I know that our operation has been ongoing for some time now and that it is causing disruption and inconvenience to local residents and the community of Northolt. I would like to thank them for their continued patience and co-operation."

He added: "The operation will continue for as long as is necessary and I would like to stress that we are doing all we can – using all our tactics – to end this incident safely."

It has also been reported that family members believe the man has recently had a "breakdown". The local authority, Ealing Council, said some elderly, vulnerable or families with young children had been placed in bed and breakfasts.

The authority's leader Julian Bell said: "The safety of our residents is our top priority and council officers will continue to be on hand to give any necessary assistance until the incident has been resolved."

A number of police vans at Wood End Lane, Northolt, where a stand-off is ongoing with a man with 'hazardous items'. @LFaurePhotos