Three key senators who led a Senate inquiry into the PwC tax leaks scandal have asked the Department of Finance to reverse a draft decision to lift a ban on the firm working for the government.

In a joint letter to the department sent last month, Liberal senator Richard Colbeck, Labor senator Deborah O’Neill and Greens senator Barbara Pocock argued “any action to restore [PwC’s] ability to seek government contracts” is premature.