French oil company Total said Tuesday that it was considering exploiting tar sands in the west central African country of Congo, where it is the chief oil and gas producer.

"In the future, there are things to do in oil and gas, and -- why not? -- tar sands," the company's director of sustainable development and the environment Jean Michel Gires told the 6th annual World Sustainable Development Forum (WSDF) meeting in Brazzaville.

"Total is taking an interest in other latitudes, because we have a presence on the issue in Venezuela, Canada and Madagascar," Gires said.

"It is a long-term issue, not an easy issue. You have to find the right technologies, the right plans to develop these very heavy oils without pollution and without having too marked an effect on the environment."

In Canada, where the Alberta tar sands hold the second largest oil deposits in the world, overseas companies said last week they were reviewing their investment plans because of falling oil prices and tighter credit.

The Italian oil company ENI in May signed a deal with Congo to exploit the tar sands at Tchikatanga and Tchikatanga-Makola in the south, estimated to hold reserves of between 500 million and 2.5 billion barrels.