Workmen in Bristol were forced to smash a car window to rescue three dogs trapped on the hottest day of the year.

The dogs were left in a car boot on Thursday with all the windows shut in 27C heat. The animals were reportedly left for two hours in a vehicle with no ventilation.

Concerned onlookers dialled 999 and urged the police to take action. A sheet was draped over the rear windscreen to give the pets (a Chihuahua, Staffie-cross, and a mongrel) some shade.

One person left a note on the car windshield which said: “Dogs die in hot cars! You have been reported to the police.”

However, the officer who arrived at the scene planned to wait until the car owners returned as a parking ticket was due to expire.

A workman from Bristol Waste decided to take matters into his own hands, using a lump hammer to smash the driver’s window and unlock a door, just before 1pm.

Once they gained access to the car, a passer-by gave the dogs a bowl of water.

The dogs were left in the boot with all the windows shut in 27C heat - after the Met Office issued a 'threat to life' warning (Bristol Post / SWNS.com)

Lisa Eastman, a colleague of the workman, said: “I stopped on the side of the road to do one of my jobs. As I stopped, the chap had the back boot opened, and I asked if [the dogs] were going to be alright.

“He said the shop did not allow dogs and he had given them some water. They have been in there since 10.40am.”

When the owner returned to the car, he reportedly had an angry exchange with onlookers. A woman accompanying him claimed the dogs had been lying on an ice mat.

“We’ve done everything we could. We rang the police, the RSPCA,” Ms Eastman added.

“I will put my hand up and say we agreed to smash the window because it was necessary and I would do it again in a second.”

The incident happened on the same day that the RSPCA revealed three dogs have died in hot cars since the start of the heatwave, which is the UK’s longest since 1976.

In a statement yesterday, the RSPCA said its emergency hotline received 3,832 calls about animals and heat exposure from 1 June to 24 July.

The organisation urged anyone who sees an animal stuck in a hot car to call 999, as only police have the authority to break into a vehicle.

If police cannot attend an incident and you believe the animal is in danger, you are advised to explain what you intend to do and take evidence, including photos of the trapped animal and contact details for any witnesses. You may be asked to defend your decision in court.