The world's biggest uranium-miner, Canada's Cameco, has temporarily halted remediation work at the number one shaft at the Cigar Lake project, in Saskatchewan, after an increase in the water flowing into the mine.

Shares in the company fell 6,34% on Wednesday morning, to C$31,89 a share by 11:29 in Toronto.

Cameco received approval to start dewatering the mine in June, after succesfully testing an underground seal.

The firm wants to get the water out so that it can assess the underground damage at Cigar Lake, which was initially expected to have begun production as early as last year, before a rock fall caused a flood in October 2006, delaying construction.

The shaft had been pumped down to 430 m below the surface, when an increase in the rate of water inflows was reported on Tuesday morning, and pumping was suspended a few hours later.

Water was flowing into the shaft at 600 m³/h, the company said.

For now, Cameco plans to allow the water level in the shaft to rise to about 100 m below the surface, which will allow it to gather data and decide what the next steps should be.

The company is working to determine the source of the inflow, and what implications it has for the remediation plan.

Cameco CEO Jerry Grandey said in May that production could begin in 2011 "at the earliest" from Cigar Lake, which contains proven and probable reserves of more than 226,3-million pounds of uranium.

Cameco, which is the operator of the project, owns 50% of Cigar Lake, while Paris-based Areva owns 37%, Idemitsu Canada Resources holds 8% and Tepco Resources owns 5%.

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