A battle between the referees union and the NRL will continue on Friday with Abdo hopeful of finalising an agreement before arbitration over the weekend.

Professional Rugby League Match Officials (PRLMO) are up in arms about the NRL's plan to reduce on-field referees from two to one for the remainder of the season, citing they were given little or no consideration before the decision was made.

A mediation with Fair Work Commission on Tuesday failed to reach a resolution.

"We are in ongoing dialogue with referees and we hope to resolve the matter (on Thursday or Friday)," Abdo said.

"If not, we have arbitration that will happen over the weekend.

"Either way we'll have an answer at the end of the weekend or on Monday.

"We're confident we will have kick off on May 28 and whether it's one ref or two refs, that's a matter for Fair Work Australia and for ourselves and the referees to decide."

The NRL has guaranteed 22 full-time referees will be employed beyond this year.

However, with just seven days until the NRL season kicks off in Brisbane, any delay in the process could threaten round three.

PRLMO chair Silvio Del Vecchio has publicly declared referees will not hold up the start of the season with strike action although it remains an option.

"At this stage there's no talk of any strike action from the refs, we're just settling a few issues that they have brought to the surface," Abdo said.

"We're confident if we haven't settled this before arbitration, then following arbitration we will be in a situation where our full-time refs will be taking the field on Thursday."

Australian Associated Press