Federal MP Clive Palmer had the final say on major spending decisions at his troubled Queensland Nickel refinery even after stepping down as a director, the ABC's Four Corners program reports.

In an episode to air on Monday night, the program claims Mr Palmer remained heavily involved in multi-million dollar spending decisions despite officially standing down from a formal role with the company following his election to parliament in 2013.

Most of the spending decisions were outlined in emails from Mr Palmer's email alias, Terry Smith, and included an $8 million haulage contract and a $6.3 million mining contract, the program claims.

The MP is facing probes by the Australian Securities and Investments Commission and Queensland Nickel's administrators into whether he acted as a shadow director before the company ran into trouble.