The Food Standards Agency said that as well as its original plans to check 224 samples of raw beef products for horse and pork DNA, it was now overseeing the testing of 140 meals such as lasagne, cottage pie and ravioli.
"This will give us a full a picture as we can possibly have," an FSA spokesman said. "We became aware that the issue was bigger than just burgers and it became sensible to look into other products too."
Nestle removed Buitoni brand beef pasta meals from sales in Italy and Spain on Tuesday, the latest European food company to find traces of horse DNA in its products.
The FSA said it would also survey a further 150 samples of products marketed as containing beef - including kebabs, gelatine, and stock cubes - as part of an EU-wide testing program.
The tests will be carried out by local authorities and include loose food, such as cafe sandwiches, it said.
The regulator said last week that it had found 29 samples of horsemeat in the food chain, in a separate swathe of tests it carried out of samples demanded from retailers.
The scandal, which has triggered product recalls and damaged confidence in Europe's vast and complex food industry, erupted last month when tests carried out in Ireland revealed that some beef products also contained horsemeat.
