OTTAWA - Atomic Energy of Canada's chief rival to build a nuclear power plant in Ontario has offered to help the federal government through the shutdown of the Chalk River reactor.

France's Areva Group wrote to two Conservative cabinet ministers last week offering to help Canada find European reactors that can make the isotopes used in medical imaging.

Areva also told Natural Resources Minister Lisa Raitt and Health Minister Leona Aglukkaq its engineers can help AECL repair the 52-year-old nuclear reactor at Chalk River, Ont.

"Areva is ready to provide all the support that you will deem necessary to reduce the health impact of the current isotope shortage," wrote Armand Laferrere, president of Areva Canada.

"We will, as requested by you, facilitate contacts with European isotope producers. We are also ready to assist technically in the NRU repairs."

The reactor at Chalk River, Ont., was shut down May 15 after a power outage in parts of eastern Ontario and western Quebec.

A heavy water leak was detected within the facility and officials said it would be out of service for more than a month while repair options are considered.

Last week, an AECL executive said the shutdown could be a long one.

The Chalk River reactor supplies up to half of the world's supply of isotopes used to detect cancer and heart ailments.

AECL ran out of medical isotopes over the weekend and doctors are scrambling to hoard a scarce supply from the world's four other isotope-producing reactors.

Laferrere said there are other European research reactors that Areva could jury rig to make medical isotopes. But he added it could take "several weeks" to make the modifications.

The French firm made a similar offer to Ottawa in late 2007 when AECL's aging National Research Universal reactor was shut down for nearly a month, sparking a critical global shortage of medical isotopes.

A spokeswoman for Raitt said in an email the natural resources minister saw the letter Monday morning and is mulling Areva's offer.

"There will certainly be follow-up on their offer of assistance," Jasmine MacDonnell said.

Areva is bidding against Crown-owned AECL and the U.S. firm Westinghouse Electric Co., to build two nuclear reactors in Ontario.

Laferrere insisted the offer has nothing to do with the Ontario bid.

"Frankly, I'd like not to link the two stories," he said in an interview.

"The one is a competitive process and we're opposed to AECL. This one, it's not about competition, it's about doing whatever everyone can to mitigate a health crisis."

The province is expected to award the reactor contract this summer, though Ontario's energy minister, George Smitherman, has said the decision could be delayed.