London: The Food Standards Agency has vowed the investigation into the horse meat scandal will be “relentless” and promised the agency would get to the bottom of the matter after meat from British horses was found in burgers and kebabs made in the UK.

The FSA director of operations, Andrew Rhodes, said investigations would continue until “there was nothing left to find”.

Pressure on the FSA is mounting after police raided two British meat companies on Tuesday in their first action jointly with food standards officials in the food fraud and the horse meat scandal.

The environment secretary, Owen Paterson, is travelling to Brussels on Wednesday for an emergency a meeting of European countries caught up in the scandal.

Officers entered Peter Boddy Licensed Slaughterhouse in Todmorden, West Yorkshire, and Farmbox Meats Ltd near Aberystwyth in Wales on Tuesday as they investigated the circumstances in which horse meat was sold as beef “for kebabs and burgers”.

But Rhodes said there was, as yet, no evidence to suggest a wider problem in the United Kingdom.

“What we have been doing at the FSA is investigating a really broad range of different things and we have actually exonerated quite a lot of businesses so far in our investigations and I am sure that will continue to be the case,” he said during a BBC Breakfast interview.

“What we are doing is focusing on the areas we think are the highest risk so we have identified documentary evidence that has led us to take the action that we have. We don’t have evidence that this is a widespread problem in the UK.”

Rhodes said five slaughterhouses in the United Kingdom processed horses on a regular basis, adding that suspicions about one of them had led to the raid near Aberystwyth. “We will continue with that investigation and we will keep pursuing this until there is nothing left to find,” he said.

He added that the FSA had seized all meat as well as paperwork and was working with police in Dyfed Powys and West Yorkshire.

The FSA has ordered food businesses to carry out tests on all processed beef products and the first results are expected on Friday, although full results could take much longer.

“We’re progressing very well through our investigations but they’re not complete yet. So I’m not going to speculate on what else we might find. But of course, we don’t really expect to find anything because if people are behaving according to the law and doing what they should be doing then there should be nothing to find,” Rhodes said .

“But that doesn’t mean that we are in any way complacent. We’ve been very relentless in this. We’ll continue following it through until there is nothing left to find.”

On BBC Radio 4’s Today programme, Rhodes denied claims that a surveillance programme had been effectively stopped previously under pressure from the supermarkets. “We still actively sample lots and lots of products,” he said.

Paterson held a second meeting with the FSA, food retailers and suppliers on Tuesday to discuss a new regime of random testing of foods. In Brussels he will discuss the growing Europe-wide crisis with the health and consumer commissioner, Tonio Borg, and his opposite numbers from France, Ireland and Romania.

The scandal spread on Tuesday after upmarket retailer Waitrose withdrew its Essential British Frozen Beef Meatballs after pork was detected in two batches.

They had been produced at an ABP Freshlink site in Scotland last summer. The plant, whose closure was announced last year, was not implicated in earlier horse or pork contamination scares at the Irish food group’s Silvercrest and Dalepak sites, in County Monaghan, Ireland, and North Yorkshire respectively.