UPDATE: A dangerous "mini-volcano" of gases and acids bubbled up though a Battersea drain.

The noxious fumes were considered such a safety hazard the home had to be evacuated.

Five engines attended Banbury Street at about 3pm on Monday, August 17, and fire fighters wearing breathing apparatus entered the home before using soda ash to neutralise the chemicals, which included sulphuric acid.

Battersea Fire Station watch manager Simon Jenkins said he believes the noxious gases were caused by contractors pouring various chemicals, including powerful drain cleaner One Shot, down the sink.

A spokesman for McCarthy Court management team, which runs the building, said the affected drain was on a balcony, and that workers had only poured 'one shot' cleaning agent into the drain.

She added that there were suspicions other cleaning products other unblockers were put down the same drain however this could not be confirmed or verified.

Mr Jenkins said: "There was a suspicion that some other stuff had been poured down the drain and resulted in the release of some nasty gases, with nasty sludge coming out like a mini-volcano.

"We took some readings and the gas levels were unsafe for humans to be there.

"There is an eggy smell and it is not pleasant at all. If you were there for a long period of time it would do you some harm."

One Shot, which is 91 per cent sulphuric acid, has been known to melt pipes and can cause the skin to bubble and blister.

The label contains a warning not to use when other chemicals are present, particularly caustic or hypochlorite bleach.

Mr Jenkins said the fire service receive many calls similar to this one because people often use products without reading the warning instructions and mix them with other chemicals.

He said: "When you do that you risk a chemical reaction, which is what we suspect happened here.

"We would suggest that if you use these sort of products that you read the instructions and don’t mix these chemicals because dangerous gases can be produced."

London Ambulance Service were called and treated a man who, it is understood, suffered no ill effects from the incident.