As a result of these investigations UK NHS Tests and Trace has suspended testing operations provided by a laboratory in England but affects some residents in Wales.
O ganlyniad i'r ymchwiliadau hyn, mae gwasanaeth Profi ac Olrhain GIG y DU wedi atal gweithrediadau profi a ddarperir gan labordy yn Lloegr ond mae'n effeithio ar rai trigolion yng Nghymru.