Police arrested the men after it emerged a significant amount of horse meat containing the painkiller "bute" could have been entering the food chain for some time.
Authorities in Britain and France are trying to trace the carcasses of six horses contaminated with bute - which were slaughtered in a UK abattoir and may have entered the human food chain across the Channel.
More top news
Warming up in the south but with breezy showers across Scotland today.
BA passengers face tighter curbs on the size of hand luggage as part of inclusive allowances for economy and premium economy travellers.
The wrestling hall of fame star 'Rowdy' Roddy Piper has died aged 61.