Explosive gas cylinders are being deliberately hidden beneath rubbish, which is then set on fire, to harm firefighters.

The canisters are often hidden under piles of fly-tipped rubbish, and used as small bombs which could seriously injure or even kill crews, say fire chiefs.

Shipley station manager Steve Nunn said crews were dealing with an average of one gas cylinder incident a day among burning fly-tipped rubbish.

Officials have condemned the fly-tippers who dump dangerous waste after another series of incidents at the weekend in which hazardous waste was set alight.

Firefighters unearthed a gas cylinder beneath a blazing pile of rubbish in a Cleckheaton street, and fire station manager Peter Phillips said: "In this case it was not intentional but sometimes they are intentionally used as bombs.

"It's not unusual to get incidents involving these gas cylinders. If they are full of gas they are like a small bomb. If they do explode, as well as forming a large fire ball, bits of metal or the debris around them can get blown about.

"Even if they are empty they could still explode if they are exposed to fire because there are still remnants of gas in them."

Fly-tippers are also putting people's lives at risk in other ways, say fire chiefs. Last week, a family had to be rescued after burning rubbish was piled against their home.

And firefighters are regularly called to blazes involving dumped glass and sharp metal as well as toxic products and flammable substances.

Dumped products include both household and industrial waste ranging from old oils and paint-cleaning fluid to gas cylinders and asbestos sheeting.

Mr Phillips said: "Fly-tipping is a big problem and we get all sorts of dangerous and hazardous materials that are damaged. It can be anything that people do not want to pay to remove and do not treat responsibly.

"They are a hazard to the public as well as firefighters. Children could be injured while they are playing on them."

Cleckheaton firefighters were called to a fly-tipping blackspot off Northgate twice over the weekend.

Watch manager Stuart Hall said: "Fly-tipping near buildings will lead to the loss of lives. There was a lot of old furniture and bedding dumped very near a building.

"Underneath the pile of rubbish was an old gas cylinder. It could have exploded and taken out one or two of my men."

Last week, four people, including a baby, had to be rescued from a burning block of flats after furniture piled against an outside wall in the Gaisby flats at Owlet, Shipley caught fire in the early hours.

Steve Nunn, station manager at Shipley fire station, said firebugs setting light to dumped furniture or wheelie bins of rubbish was a problem in the Shipley area.

He said: "Residents leave their furniture in the bin area, which is close to the communal staircases in the flats, to be collected by the Council. Then you get idiots setting fire to them and it smoke-logs the staircase."

Mr Nunn said Shipley crews also had problems with rubbish being dumped in the open, which is then set alight.

He said: "People seem more prepared to dump than go the extra few yards to the tip. We are becoming more aware of it. People need to be careful where they put their wheelie bins out. If they are set alight the fire is small but intense and severe."

Mr Nunn said crews were probably dealing with an incident a day where potentially explosive cylinders are involved.

"We approach rubbish fires with great caution, especially now during the school holidays, because you never know what's under there. We have to be very defensive in the way we approach the fire.

"One of these days one of these cylinders is going to go bang and when it does, someone will get hurt."

Acting Inspector Paul Hepworth, of Bradford North Police, said officers and Police Community Support Officers who saw evidence of fly-tipping while on patrol would report it to the Council's environmental health department.

He said: "If anyone sees any fly-tipping they should report it to us and we will notify the Council department."

Bradford Council deals with more than 5,000 fly tips a year which costs more than a quarter of a million pounds.

Bradford Council's head of service waste and street scene, Ian Bairstow, said: "We are regularly receiving fly tip tyres, gas bottles, furniture, bags of rubbish and garden waste and we get building waste and asbestos.

"The problem is when gas bottles are obscured by other waste such as furniture. There is a significant risk to people from fire, exploding gas bottles, noxious smoke from tyres and the potential for fire to spread to properties.

"There is no reason why Bradford residents need to fly tip. They can take household waste to household waste recycling centres where they can dispose of it free of charge."