A massive fire involving plastic pipes in fields along the Marsa racecourse pumped plumes of "poisonous" black smoke into the sky as people were warned to avoid the area on Tuesday morning. 

Emergency services were called to the site at around 11am after thick smoke was seen as far away as Mellieħa. One person was treated for heat exhaustion.

Tony Pisani, Chief Assistant Rescue Officer said more than 20 firefighters were involved. 

He said the burning of the PVC pipes released carbon monoxide, which he called “the poison of fire”.

Smoke from the fire trailing in the breeze above homes and businesses. Photo: Jonathan Borg

“There were about four layers of stormwater pipes stacked on top of each other,” he said.

“They’re made of plastic and they were exposed to the heat. It could have been there was some grass around the pipes, although I cannot say for certain.

“Even if there was a bit of metal laying around, when it is this hot and if the heat concentrated on a particular spot it could start a fire that gets caught by the wind and spreads."

Martin Polidano from the Water Services Corporation, who was at the scene, confirmed a number of large PVC pipes were being stored on site and caught fire. 

Pisani said firefighters had to call for backup after realising the extent of the blaze, which was under control by Tuesday afternoon. 

"We first sent a small unit but once they got close to the blaze they realised that they would not be able to work with the resources at hand," he said.

"They called for backup and we brought vehicles from Ħal Far, Xemxija, Delimara, because the fire was so intense we could not approach it.

Plastic pipes were being stored on site and caught fire. Photo: Jessica Arena

Pisani also appealed to farmers not to start grass fires as the CPD is being inundated with calls about small fires that spread after farmers set their cut grass on fire.

“This is not the time to burn grass, please leave it a little longer and burn it as winter approaches, maybe in October or November,” he said.

“We are going out on a lot of these types of calls and our resources are being spread thin among a lot of small fires and when a big job like this one happens we have to scramble back to the stations to deal with it. No matter how many people we have, they cannot be everywhere.”

The Marsa fire seen from Kappara. Photo: Times of Malta reader

Photo: Jonathan Borg

Police initially described it as a grass fire but Home Affairs Minister Byron Camilleri said it was caused by plastic and tyres. 

"I'm informed that in the area of ​​Marsa, in the fields surrounding the sports complex and the horse track, a fire has developed caused by plastic ducts and tyres," he said.

"Everyone is asked to avoid the area."

It is understood some trees have been destroyed in the blaze. However it appears the fire did not go beyond the tree line, which borders a property that has stables for horses.

So far no human or horse injuries have been discovered. 

Transport Malta were on site, closing roads and diverting traffic towards Sta Venera. 

It comes as Malta swelters under a heatwave, with temperatures forecast to reach as high as 40 degrees on Tuesday.

The Met Office issues a red (take action) warning as the UV index is expected to reach 12.  

In a statement in the afternoon, the Water Services Corporation said sewer replacement works were being carried out by a contractor and a number of pipes had been destroyed by the blaze.

It said it and the contractor were collaborating with the police in their investigations.