FORT MCMURRAY, Alta. — Syncrude's brand new, $8.4-billion oilsands expansion in northern Alberta is being temporarily shut down because of foul, urine-smelling emissions.

Alberta Environment issued an order Thursday afternoon calling on the joint-venture oilsands giant to immediately shut down its new "flue gas desulphurization unit and attached equipment," related to the Mildred Lake plant located 40 kilometres north of Fort McMurray.

The order followed numerous complaints about unpleasant odours this week from residents of Fort McMurray and the nearby hamlet of Fort McKay.

"We have been deeply concerned about the odour complaints resulting from the start-up of our expansion project and will continue to work with Alberta Environment and regulators to determine the cause of the recent odours and take appropriate steps to rectify the situation,'' Syncrude president Jim Carter said in a release late Thursday.

The shutdown will involve Syncrude's new Coker 8-3, one of three massive cokers used at the sprawling Syncrude site. The new coker is an integral part of Syncrude's $8.4-billion Stage 3 expansion which began coming on-line earlier this month after several years of construction and billions of dollars in cost overruns.

The cokers are a key part of processing the gluey bitumen, using high temperatures to remove some of the carbon molecules and some of the byproducts like petroleum coke.

Syncrude, jointly owned by a group of oil and gas firms, is Canada's largest oilsands producer, averaging about 205,000 barrels per day earlier this year. The Stage 3 expansion is designed to boost production by more than 50 per cent to 350,000 barrels per day.

Alberta Environment Minister Guy Boutilier, a resident of Fort McMurray, said the emissions were not only foul smelling, but seemed to be causing eye and skin irritations.

"It's my understanding that it's a smell of urine that people were experiencing," Boutilier said Thursday.

"But also it's my understanding there is other types of odour that is creating irritation," he said.

"Right now our most important concern is ensuring the safe operation of the plant and the smell that people are experiencing in my community is alleviated. Of course I expect the enforcement orders that were issued by Alberta Environment officials will be followed by Syncrude and I understand that's exactly what's happening.''

Canadian Oil Sands Trust, which has the largest stake in Syncrude at 35.5 per cent, said it believed that the odour problem with the new coker was likely related to the desulphurization unit.

"It is a disappointment, for sure, because you hope that everything runs smoothly,'' said spokeswoman Siren Fisekci in Calgary.

"However, we've always indicated that we do expect that it won't necessarily be an entirely smooth process as you bring these units on line, and that there might be hiccups."

"This is one of them, in our view."

The flue gas desulphurization unit is a new technology that the company expects will virtually eliminate sulphur dioxide emissions from the facility when fully operational.

The plant was undergoing a "safe shutdown" Thursday afternoon and Alberta Environment was monitoring the ambient air quality in both nearby communities.

The environmental protection order directs Syncrude to submit a detailed action plan to address the odorous emissions and the plan must be approved by the province before the desulphurization unit can be restarted.

Before the shutdown, Syncrude said it was seeking advice from scientists and specialists to help pinpoint the cause of the odours.

Three weeks ago, five children from Fort McKay were taken to hospital after an ammonia leak at the same plant wafted over their nearby community.

Other Syncrude owners include Calgary-based Imperial Oil Ltd. with 25 per cent, as well as Petro-Canada and Nexen Inc., along with Houston-based ConocoPhillips, Mocal Energy and Murphy Oil.