The West Coast rugby team fielded an ineligible player during this season's Heartland Championship.

An administrative error will cost the West Coast Rugby Union up to $4000.

The union's Heartland Championship team fielded an ineligible player across the first four rounds of this year's competition.

The player was listed as a local, but did not meet the criteria to be classed as one.

West Coast won just one of those four matches, although they did pick up bonus points in losses.

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WCRU brought the breach to the attention of New Zealand Rugby after discovering the error and immediately stood the player down.

A New Zealand Rugby-appointed panel accepted the WCRU's explanation that the breach was the result of an administrative error and was not deliberate.

Half of the $4000 fine will be suspended and only payable if the should they breach eligibility regulations again during the next five years, an NZR statement said on Wednesday.

There was a consideration to deduct competition points, but the panel determined this would be an "unfair penalty in the circumstances of a non-deliberate breach".

West Coast sit seventh heading into their final match of the regular season this weekend against winless East Coast.

A win would secure a place in the Lochore Cup semifinals.