Two technicians working on a fire-suppression system at an Antarctica scientific station were found unconscious and died, the US National Science Foundation says.

The foundation says the two had been working in a building at McMurdo Station, which is on Ross Island.

They were found on the floor by a helicopter pilot who had landed after spotting what appeared to be smoke from the building.

(9News)

One died at the scene, the other died in a clinic shortly afterwards. (AAP)

Both were taken from the building and given CPR; one died at the scene.

The other was flown to a clinic and pronounced dead shortly after.

The pair was employed by a Virginia-based subcontractor and the deaths are under investigation.