HSE officials legally "shredded" files relating to the controversial cervical cancer labs tender process, meaning they cannot now be examined by State investigators.

The Dáil's public accounts committee was told of the situation just 24 hours after lead investigator Dr Gabriel Scally told the Dáil's health committee he cannot be certain he has been given all of the files.

Speaking during an early morning meeting of the PAC, Labour health spokesperson Alan Kelly said he has serious concerns over the ongoing lack of transparency on why a US firm central to the scandal was allowed to outsource its work to another company.

Noting similar concerns from Dr Scally, Mr Kelly said "they [the HSE] actually shredded them when the time limits were up" in what he labelled as an unusual example of "the one time the HSE has been efficient" on the matter.

Dr Scally said [at Wednesday's health committee meeting Mr Kelly also attended] said he cannot guarantee, even now, that the HSE has provided him with every document.

"He said he cannot and doesn't know if there were other examples of outsourcing, and he doesn't know where it begins or ends," Mr Kelly said.

The Labour TD's concerns were added to by Fine Gael TD Kate O'Connell, who said it is deeply worrying "tenders have been shredded" and that there are obvious concerns about trusting the firms involved to "give them [their copies of files] to us".

The PAC is due to meet Dr Scally and ex-Cervical Check clinical director Gráinne Flannelly in the coming weeks.