Alberta's environment minister said the provincial government's efforts to allay environmental concerns about its booming oil sands industry will be hurt by the deaths of hundreds of ducks that landed on a pond filled with toxic waste.

Environment Minister Rob Renner concedes the deaths have put a dent in Alberta's efforts to counter the message being spread by environmental groups that Canada's oil sands projects are taking a toll on the environment.

"It's a real blow to our messaging that we are working very, very hard ensure that we do have sustainable development," Renner said.

The government is investigating the incident in which about 500 birds landed and died in the oil sands pond. The pond full of toxic sludge sits along a major flight path for migrating waterfowl.

The province requires that all such ponds have noisemaking devices to scare the birds and prevent them from landing.