The James Bay Cree Nation has filed a lawsuit seeking title to about 48,000 square kilometres of land in northeastern Ontario.

The lawsuit, which has been filed with Ontario's Superior Court of Justice, names the federal and Ontario governments and claims damages of $495 million in relation to the Eeyou Istchee-Ontario lands.

The suit claims the two governments have "unjustifiably infringed" on the Cree Nation's title and rights — and breached their trust and obligations to the First Nation.

The suit also claims Ontario and Canada have been "unjustly enriched as a result of their breaches of the plaintiffs' aboriginal title and other aboriginal rights … and the plaintiffs have suffered."

The claims outlined in the suit have not been tested in court.

A spokesman for Ontario's ministry of the attorney general says lawyers are reviewing the claim, but Brendan Crawley adds it would be inappropriate to comment further as the matter is before the courts.

Grand Chief Matthew Coon Come calls the suit the latest chapter in the Cree Nation's struggle to ensure that its pre-existing rights over all of its traditional lands are properly respected.

"The imposition of the Ontario-Quebec boundary cut through our homeland of Eeyou Istchee," Coon Come said Monday in a release.

"Our people have used, occupied, governed and protected these lands in Ontario since time immemorial, but our rights in these lands have never been addressed in any treaty," he said.