In one sample from a Tesco beefburger, horsemeat accounted for approximately 29% of the meat content, the FSAI said.

BBC: UK

Iceland said the FSAI's findings were concerning, stressing the company had "withdrawn from sale the two Iceland brand quarter pounder burger lines implicated in the study".

BBC: 'Horsemeat beefburgers' investigated in UK and Ireland

Ms Brown told MPs the Food Standards Agency of Ireland (FSAI) investigation had found the Polish supplier was used by the Silvercrest facility for about 12 months.

BBC: Horsemeat row: Trade union's fears over Silvercrest jobs