The Harper government will use a visit by the French prime minister to burnish its tarnished reputation in Europe on energy and the environment.

The Canadian Press has learned France and Canada will sign a joint declaration Thursday on a research co-operation initiative that will focus on creating biofuels from seaweed.

Prime Minister Stephen Harper, right, welcomed French Prime Minister Jean-Marc Ayrault to Parliament Hill Wednesday, where the two were expected to discuss Canada-EU trade talks among other topics. (Sean Kilpatrick/Canadian Press)

The announcement, to come prior to a joint press conference Thursday with Prime Minister Stephen Harper and his visiting French counterpart, Jean-Marc Ayrault, builds on last year's breakthrough in biofuel technology when scientists found a way to use seaweed as an alternative fuel source.

That discovery helped alleviate the controversy around using corn to create ethanol, because critics questioned the use of food as an energy source.

The co-operation deal is also important for the Harper government because Alberta oilsands crude faces being labelled as "dirty oil" by a European Union committee sometime soon.

The EU's proposed new Fuel Quality Directive would assign greenhouse gas emission values to different sources of fuel, sparking Canadian concern that oilsands crude would be unfairly categorized.