Cladding similar to that used in four council tower blocks in Swansea has passed a new fire safety test in the wake of London's Grenfell disaster.
Residents of flats in Clyne Court, Sketty, and Jefferys Court, Penlan, were concerned when the material used failed initial tests.
Communities Secretary Carl Sargeant hailed results of a new whole-system test as a "positive development".
It follows the failure of a system test on material used in Newport.
At least 80 people died in the Grenfell fire, and the UK government demanded urgent fire tests on all tower blocks.
Since then, the Building Research Establishment (BRE) has been carrying out whole-system tests to judge the risk of fire spreading from panels made of aluminium composite material (ACM) to entire buildings.
In a written update to assembly members, Mr Sargeant said one set of results related to tests on material "similar to the combination in place on four buildings owned by the City and County of Swansea, samples of which had previously been tested by the BRE".
This featured ACM with a fire retardant polyethylene filler with mineral wool insulation.
"The tested system passed the test, which is a positive development," Mr Sargeant said.
"Of course, landlords and owners must continue to draw on all expert advice and guidance in relation to their individual buildings."
Andrea Lewis, Swansea council's cabinet member for housing, welcomed the "very reassuring news" which she said backed up the authority's own whole-system test of the cladding system used.
She added that work to fit sprinklers in all 11 of the council's high-rise blocks would begin in November, with priority given to those with exterior cladding.
Earlier in August, it was confirmed that a whole-system test on material used in three tower blocks owned by social landlord Newport City Homes had failed.
Rockwool, the makers of the insulation involved, said the test did not properly assess their product.