(Adds diesel spill, details on rail line and Cliffs' Bloom Lake mine)
By Allison Lampert
MONTREAL, Nov 6 (Reuters) - A train operated by Rio Tinto Plc's Iron Ore Company of Canada derailed in Quebec and its single operator was missing following an apparent landslide, the Canadian iron ore miner said on Thursday.
Early information indicated a landslide had caused the derailment of the train, which was transporting empty cars from Sept-Îles, Quebec. A locomotive was found submerged in water, the miner said in a statement.
The company said all railway traffic was suspended until further notice.
"We will do our own investigation to determine the cause," said Claudine Gagnon, a spokeswoman for Rio Tinto. "Our priority is to find our employee."
Some diesel spilled from the locomotive that plunged into the river, said Frédéric Fournier, a representative of Quebec's environment ministry. He could not say how much had leaked, but noted that the locomotive carried about 17,000 liters of diesel.
"We are now working to minimize the impact of the derailment on the river," he said.
Iron Ore Company of Canada, majority-owned by Rio Tinto, owns and operates the Quebec North Shore and Labrador Railway, which links its mine to port facilities.
The railway also carries iron ore from Cliffs Natural Resources' Bloom Lake mine. A Cliffs spokeswoman said it was too early to speculate about the impact of the derailment.
Gagnon said the line mainly carries ore for Iron Ore Company of Canada and other clients. Trains also carry general freight, including fuel, material and equipment for mining companies and the communities of Wabush and Labrador City in Newfoundland and Labrador and Schefferville, Quebec.
The line is used twice a week for passenger service, with the next scheduled departure from Sept-Îles on Monday.
Derailments have become a particularly sensitive issue in Canada since a crude oil train crash in Lac-Megantic, Quebec, in July 2013 that killed 47 people. That train also had only one operator, an unusual practice in the North American railway industry. The only other railway cleared to run one-person trains in Canada was the Quebec North Shore and Labrador Railway.
Quebec Provincial Police said they received a call at around 7:30 a.m. ET Thursday about the train's derailment in a remote location north of Sept-Îles.
Police had difficulty accessing the site, about 950 kilometers (590.3 miles) northeast of Montreal.
"It's a very isolated site, located in the forest," said Sergeant Claude Doiron of the Sûreté du Québec.
Toronto Stock Exchange-listed Labrador Iron Ore Royalty Corp owns 15 percent of the company, and Japan's Mitsubishi Corp owns 26 percent. (Writing by Allison Martell in Toronto; Additional reporting by Sneha Banerjee in Bangalore; editing by Chizu Nomiyama, Bernadette Baum and Matthew Lewis)