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.
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1.5m European citizens will miss out on the chance to vote on whether Britain stays in or quits the EU.
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Ireland's overwhelming support for gay marriage is a message to the world, UN secretary general Ban Ki-moon said.