The Beaverbrook Art Gallery has been accused of trying to "rewrite history" by lawyers for a British-based foundation that is claiming ownership of 133 paintings at the prestigious institution in Fredericton.

At stake at an arbitration hearing are rare paintings worth up to $100 million that the gallery insists were gifts from British press baron Max Aitken, also known as Lord Beaverbrook.

The British Beaverbrook Foundation, a charitable group, claims the paintings were simply a loan, and that the organization should be able to take them back.

The paintings have been housed in Fredericton for more than 40 years.

Lawyer Kent Thomson spent Wednesday attempting to dismantle the gallery's arguments that it should keep the paintings.

The gallery has acknowledged the foundation's ownership of the paintings on its own website, as well as on brass plaques that had been fastened on the front of each of the paintings until the dispute arose in 2004, he told arbitrator Peter Cory, a retired Supreme Court Justice.

Thomson said the plaques had been on the paintings since at least 1972, but were removed prior to a gallery exhibit of the works in dispute in 2005.

All that remained of the nameplates during the show was the shadowy outline of where they had been on the frames, Thomson said, adding the gallery had not bothered to notify the foundation of its decision to remove them nor sought the foundation's approval to do so.

He said the gallery was trying to "wipe out evidence" that the paintings are the property of the foundation.

The hearing is expected to last another three to four weeks. It's expected the foundation will present Max Aitken, the current Lord Beaverbrook, as a witness.