Polish authorities found signs of horse DNA in beef stored at three storage facilities after several countries pointed to Poland as one of the sources of tainted meat that has shaken up the European food industry.
Officials in Ireland, Britain, Germany, Italy and the Czech Republic have reported that products such as burgers and lasagne contained horsemeat that originated from facilities in Poland.
Poland's General Veterinary Inspectorate said in a statement late on Wednesday it found three tainted samples from 121 tested, with 80 more to be examined.
Polish officials had previously said they found no signs of horse meat at all abattoirs tested.
A European scandal erupted last month when tests in Ireland revealed some beef products contained horse meat, triggering recalls of ready-made meals in several countries and damaging confidence in Europe's vast and complex food industry.
Poland exports 330,000 tonnes of beef products annually, or more than three-quarters of its total production, mainly to other European Union members.
(Reporting by Chris Borowski; Editing by Alison Williams)