Cafodd Llywodraeth Cymru wybod yr wythnos diwethaf am adroddiadau bod nifer uwch na'r disgwyl o brofion llif unffordd positif wedi arwain at ganlyniadau profion PCR negatif a bod Asiantaeth Diogelwch Iechyd y DU (UKHSA) yn ymchwilio i hyn.
Welsh Government was made aware last week of reports that a higher than expected number of positive lateral flow tests were resulting in negative PCR tests and that this was being investigated by the UK Health Security Agency (UKHSA).