An environmenal group has accused the government of Western Australia of reneging on a promise to stop using native hardwoods for railway sleepers.

The Global Warming Forest Group (GWFG) made the accusation after claiming that thousands of freshly-cut jarrah, marri and wandoo sleepers have been discovered at a government rail depot near Bunbury.

The group said in 2004 the government stopped supplying contracts for tenders which used rare native trees to manufacture and supply sleepers.

GWFG said the use of jarrah and other timbers in railway sleepers caused an outcry in the early 1990s, when British Rail and the Dutch government refused to accept exported railway sleepers from Western Australia after research suggested native forests were not being logged sustainably.