White House spokesman Hogan Gidley said on Wednesday that he has never seen a nondisclosure agreement in the White House under the Trump administration.

"I can't speak to anybody else. What I can tell you is I've never seen one in this White House. I've never been asked to sign one in this White House," Gidley told Ned Ryun on Hill.TV's "Rising," when asked whether he signed an such an agreement while working in the administration.

The Trump campaign hit back against Manigault Newman on Tuesday when it filed for arbitration, saying she violated the terms of a 2016 nondisclosure agreement by publishing the book.

Manigault Newman has said she signed a confidentiality agreement with the Trump campaign but denied signing a similar agreement upon departing the White House.

The White House has recently confirmed its practice of requiring employees to sign nondisclosure agreements.

Press secretary Sarah Huckabee Sanders on Tuesday did not say whether she has signed an nondisclosure agreement but said it was common for government employees, particularly those with security clearances, to sign such agreements.

Government watchdogs have argued that the documents are unenforceable and uncommon for public employees.