Labor senator Penny Wong accuses the government of trying to ‘cover up’ its handling of the Brittany Higgins allegations. During a Senate estimates hearing on Tuesday, department officials refuse to answer questions about an investigation into who knew what when in the prime minister’s office about the former Liberal party staffer's allegation she was raped in a ministerial office by a colleague in 2019. Phil Gaetjens, the head of the Department of Prime Minister and Cabinet who is running the investigation, will not say how many staff he has interviewed in the PMO. ‘It’s hardly an open and transparent inquiry,' Wong says. Fellow Labor senator Katy Gallagher says Gaetjens is conducting ‘secret interviews into a secret report’. Wong says: ‘Let’s be clear it is part of a cover-up and a deferral of being clear with the parliament.' Finance minister Simon Birmingham says he will take on notice the question about whether the report will be made public