The public inquiry into allegations of historic sex abuse in Parliament will have access to 'all the government papers, reviews and reports it needs', Theresa May has said.
She added it would also have the power to call any witnesses subject to the constraints of any criminal investigations.
The inquiry, which will last is expected to eight to 10 weeks, will not report in full before the general election but updates will be provided before the poll.
The Baroness says she did not consider the "difficulties" caused by her background and family connections to the child sex abuse inquiry.
Questions have been raised of former High Court judge Baroness Butler-Sloss since her appointment last week.
22 police officers are now assigned to Operation Fernbridge - the probe into claims of a Westminster cover-up of sex child abuse.