ABC chairman Jim Spigelman has lashed out at the Turnbull government, accusing it of posing a "fundamental challenge to the independence of the ABC" by attempting to influence the broadcaster's staffing policies.

The government is furious with the ABC over a new three-year pay deal with its employees that includes 2 per cent annual pay rises, a $500 sign on bonus, two weeks' extra paid parental leave and a new provision for domestic violence leave.

The government believes the deal is too generous given the state of the federal budget and the ABC's complaints about funding cuts over recent years.

Employment Minister Michaelia Cash wrote to the ABC in September to say it was "required to comply" with the government's tough workplace bargaining policy which disallows such benefits.