Amsterdam police on Thursday rescued a number of dogs from six cars parked outside the Rai exhibition centre were what is billed to be the world’s biggest dog show is taking place.

Police smashed car windows to free the dogs which were in the conference centre car parks. The temperature in the car parks was between 25 and 30 degrees but it could have reached 40 degrees inside the cars, news agency ANP said on Friday.

Police intervened on the advice of vets. Three of the dog owners were given fines of €750 and three others were let off with a warning, ANP said.

Amsterdam’s new city administration plan to ban dog shows from taking place in the city and animal rights campaigners have also been urging change.

‘The dogs show is praising dogs with features so exaggerated they would never have been born in nature,’ Debra Wolford, spokeswoman for Peta Nederland, told DutchNews.nl.

‘Pugs with absurd flattened faces, dachsunds with legs too short for their bodies and bulldogs with heads so big they can only be born by cesarean section – these are just some of the examples. Everyone who likes dogs should avoid these sorts of freak shows.’

Some 30,000 dogs from 74 different countries are on show at the Amsterdam event, which runs until Sunday, when the ‘best dog in the world’ is due to be chosen.