French nuclear energy conglomerate Areva said on Thursday it had beefed up safety procedures at two uranium mines in Niger after green activists said contaminated scrap metal from the facilities had been discovered at a local junkyard.

A nuclear watchdog association, CRIIRAD, and a group in Niger called Aghir In'Man said 1,600 tonnes of metal used in uranium extraction had been hauled out of the mine complexes at Arlit and were now in the public domain.

They said that around 1,000 tonnes of this had been found at a scrap metal dealer's, where handheld Geiger counter measurements in August showed gamma radioactivity levels to be "more than nine times greater than normal."

"There remains doubt about the fate of the other 600 tonnes," the groups said in a press release. "Part of this scrap may have been sold abroad."

Questioned by AFP, Areva confirmed that last August drills, scaling machines for tunnelling and other disused tools had been taken out of the Somair and Cominak sites.

"As soon as we were aware (of the practice), we immediately stopped the removal of all scrap from the sites," it said.

"These items had traces of radiological contamination that were of no consequence for public health. Levels of radioactivity were very low, as the tools had only been in occasional contact with the (uranium) mineral, which in itself has a low radioactivity level."