McClean Lake is about 800 kilometres northeast of Saskatoon. (CBC)

The uranium mill at McClean Lake, Sask., will close next summer, resulting in about 140 layoffs, but company officials say it will reopen when the economy improves.

Areva owns 70 per cent of the mill, while Denison Mines Corp. and OURD Canada Co. Ltd. own the remainder.

Denison said Tuesday that the McClean Lake project is being placed on "care and maintenance" mode, starting in July 2010.

The mill has been processing ore from several open pit mines at the site but has used stockpiled ore since mining ceased in late 2008.

When the mill closes, about 114,900 tonnes of low grade ore will have been stockpiled, Denison said.

The company didn't provide a date for reopening, saying processing will begin again "when economically viable."

The layoffs will take place at the mill site and Areva's office in Saskatoon. Areva employs about 270 people at McClean Lake and about 200 at the Saskatoon office.

While the mill is closed, some key staff will be kept on to prepare for the day when it reopens, Denison said.

When that happens, it will continue to process ore from the Cigar Lake mine or from the Caribou, Midwest and McClean North uranium deposits, the company said.

The mill is west of Wollaston Lake, about 800 kilometres northeast of Saskatoon.