The Trump administration said Friday that it will withhold 20 emails between two Trump administration aides regarding the freeze of a congressionally mandated military aid package for Ukraine.

The administration admitted there were emails between a top aide to President Trump's acting chief of staff and a colleague at the White House's Office of Management and Budget (OMB) discussing the freeze. However, it said in a response to a Freedom of Information Act (FOIA) lawsuit brought by The New York Times that it would not hand over any of the 40 pages from the exchange.

"All 20 documents are being withheld in full," wrote Dionne Hardy, the office's FOIA officer.

The Times first filed the information request to receive details on the email exchange between Robert Blair - a top aide to Trump's acting chief of staff, Mick Mulvaney - and Michael Duffey, an official in the OMB who handled the process for releasing the millions in aid to Ukraine.

Hardy said conversations about the president's staff and internal policy deliberations are exempt from FOIA requests, and added that releasing the documents from the emails would "inhibit the frank and candid exchange of views that is necessary for effective government decision-making."

Times lawyer David McCraw said the paper would challenge the ruling and ask the judge for the case for an accelerated schedule for arguments due to the urgent public interest in learning of the issue.

The withholding of the military aid to Ukraine is at the heart of the House's impeachment investigation. Democrats allege that Trump leveraged the $391 million to pressure Kyiv to investigate former Vice President Joe Biden, a chief political rival.