PARIS — A new task force in France has been given a broader mandate to search for and return artwork that had been looted or sold under duress during the Nazi occupation, after years of criticism that its restitution efforts were not proactive enough.

The task force, announced last year and starting work in the coming weeks, will primarily look at artwork in France that is already suspected of having been looted during World War II, to try to return it to the original owners or their heirs.

But in a step up from current policy, it will also try to determine whether any other pieces acquired by French institutions have dubious origins, though those are only expected to represent a small fraction of France’s vast national art collections.

“We are not starting from nothing, but we are amplifying the work,” David Zivie, a Culture Ministry official who is expected to lead the new task force, said in an interview.