Rio Tinto (ASX: RIO) has welcomed the Federal Court's move to dismiss a case to a non-union workplace agreement affecting its iron ore operations, while the Construction, Forestry, Mining and Energy Union (CFMEU) said it was considering a High Court appeal.

Justice Robert Buchanan threw out the CFMEU's challenge to the validity of an employee collective agreement struck by the mining giant directly with a group of employees in 2008.

After the Labor party halted the creation of new Australian Workplace Agreements, the mining giant made non-union collective agreements with terms and conditions similar to that of the AWAs.

Sam Walsh, Rio's chief executive iron ore and Australia confirmed the miner's plan to continue to deal directly with its staff.

He said in a note to employees that the terms of the agreement applied to all who had entered the company since July 2008 and who would have previously been covered by an AWA.

According to Mr Walsh, the court case seemed to be a step to destabilise the whole business for the purpose of enriching the interests of the union.

"During the course of the court challenge, the CFMEU confirmed that one of its interests in having the agreement declared invalid was to enable it to pursue steps to commence industrial action against the business," he said.

"Given that the CFMEU can only legally represent a small portion of our employees, and during the hearing confirmed they were representing only 31 employees out of the approximately 2000 employees the (agreement) currently applies to, the challenge to the safety net of employees across the business for the purpose of destabilising the whole business was particularly disappointing."