Uranium miner Cameco has stopped digging at its Cigar Lake mine in northern Saskatchewan due to concerns about water and weak rock formations.
The Saskatoon-based company is one of the largest producers of uranium in the world and Cigar Lake is believed to be one of the world's richest uranium deposits.
Production started on March 13 after years of delays caused by flooding problems. The company plans to go into full production in 2018.
However, on Wednesday, it announced problems in a water-saturated area more than 400 metres below the surface.
The company has been freezing parts of the mine to allow boring with high-pressure water jets to continue, but that hasn't gone as well as hoped.
The freezing is done by piping a brine solution into holes drilled in the rock.
"We have decided to temporarily stop jet-boring at Cigar Lake to allow the ore body to freeze more thoroughly in these areas," the company said in a news release.
"The additional freezing will allow more continuous production at the mine once the mill is operational."
The change means some ore production that had been planned for 2014 will be pushed into 2015.
The company says its target of producing 18 million pounds of triuranium octoxide annually by 2018 won't change.