A former Rio Tinto worker who was sacked after saying "f--k you" to a supervisor who confronted him about alleged unsafe conduct has had his unfair dismissal claim rejected by the Fair Work Commission.

Trevor Godfrey was dismissed from his job as a production operator at Mount Thorley Warkworth mine in the Hunter Valley in October 2013, after the company accused him of breaching safety procedures and using abusive language when his supervisor spoke to him about the breach.

Rio Tinto paid $US4.5 billion in tax in 2015. Credit:Louie Douvis

Mr Godfrey denied both allegations, alleging he was a victim of bullying and harassment and asking to be reinstated to his former position.

Mr Godfrey's employer, Coal and Allied Mining Services, alleged Mr Godfrey had acted against the company's safety policy by driving over a windrow containing large rocks, some as big as basketballs.