Three men were arrested last night by officers investigating the horse meat scandal.

They were arrested at plants in Todmorden, West Yorkshire and Aberystwyth, which were inspected on Tuesday by the Food Standards Agency.

A Dyfed-Powys Police spokesman said: “At Farmbox Meats near Aberystwyth, Dyfed-Powys Police have arrested two men aged 64 years and 42 years, and in a simultaneous operation police arrested a man aged 63 at the Peter Boddy Slaughterhouse in Todmorden, West Yorkshire. Approvals for both operations were suspended yesterday by the FSA so neither firm was operational.”

He said they were arrested on suspicion of offences under the Fraud Act and were being detained at Aberystwyth Police Station where they will be quizzed by police and FSA staff.

The two plants became the first UK suppliers suspected of passing off horse meat for beef. Production at both plants was suspended pending investigations into claims they supplied and used horse carcasses in meat products purporting to be beef for burgers and kebabs. The FSA said on Tuesday it had “detained” all meat found at the premises and seized paperwork and customer lists from the two companies.

It comes as it emerged a significant amount of horse meat containing the painkiller phenylbutazone, or ‘bute’, could have been entering the food chain for some time.