Last night the PAC said the group's two former executives will be given two weeks to comply – after which they will be legally obliged to attend a Committee meeting.
The PAC will also write to individuals at the HSE and other related bodies asking them to come forward.
Chairperson John McGuinness says Ms Kerins and Mr Flannery should co-operate now.
He says there'll be no escape once legal powers are secured:
