Horse meat in school dinners The crisis could escalate further after two major catering companies which supply schools and hospitals discovered horse meat in lasagnes and ready meals. The Department of Health has written to all NHS and social care providers to tell them to make sure they carry out checks on the "authenticity of food." In other developments: A British meat importer which supplies schools and restaurants was raided by the Food Standards Agency. Documents and computers were seized at two other premises. In Northern Ireland a range of burgers sold to hospitals was withdrawn after officials confirmed that they contained equine DNA. A French company accused of passing off horse meat as beef used in Findus lasagnes said it may have to close down after customers deserted it. In Lancashire, horse DNA was found in cottage pies sent to 47 schools. The council's laboratory has been carrying out DNA tests on samples collected by trading standards officers. Preliminary results show the presence of horse DNA in the school meals, which have been withdrawn. On Friday night Pauline Knowles, whose five-year-old daughter attends the Great Wood primary school in Morecambe, Lancs, described the disclosure as "very concerning." She said she would start giving her daughter more packed lunches in the future. She said: "I think it is appalling really, that it has not been tested before it has even got to our schools. The fact that horse meat is being passed off as beef, I think is disgusting. Justine Roberts, the chief executive of Mumsnet, said: "Today's news that horse meat has been found in cottage pie delivered to schools in Lancashire underlines the fact that the low-cost catering firms who often supply schools and hospitals are, if anything, more vulnerable than the big supermarkets." Sheffield council on Friday suspended the use of all processed meat in school meals with immediate effect as a precaution. Staffordshire county council has also withdrawn processed beef, while Worcestershire county council is conducting DNA tests on school meals. Brake Brothers, a company which supplies hospitals and schools with meals, was on Friday contacting its customers after one of its lasagnes was found to contain horse meat. The contamination in two samples was discovered by Whitbread, which is supplied by Brake Brothers. Whitbread owns Premier Inn, Beefeater Grill and Brewers Fayre. Brake Brothers on Friday severed links with Pinnacle Foods, the company which supplied it with the contaminated minced meat. Compass Group, one of the biggest school food providers in the UK, found between 5 per cent and 30 per cent horse DNA in beefburgers it sold in Ireland and Northern Ireland. The burgers were produced by Rangeland Foods in Co Monaghan, which has previously been implicated in the scandal. The business services organisation in Northern Ireland, which provides meat for health trusts, said one of its product ranges had tested positive. The Food Standards Agency announced that 29 out of 1,929 samples had tested positive for significant quantities of horse meat. The FSA on Friday raided Flexi Foods, a Danish-owned company based in Hull. The company imported 60 tons of beef from Poland which was later found to be contaminated with up to 80 per cent horse meat. Another company in north London where the beef was stored before being taken to Hull was also raided.