OTTAWA - The National Gallery of Canada says a plan to sell a Marc Chagall painting "was not made lightly" and would allow it to buy an Old Master painting key to bolstering its collection of French art.

Director and CEO Marc Mayer says the gallery is pursuing Jacques-Louis David's neoclassical masterpiece, "Saint Jerome Hears the Trumpet of the Last Judgment," painted in 1779.

The purchase would be funded with proceeds from the sale of "The Eiffel Tower" by Marc Chagall, which is hitting Christie's auction house in New York on May 15.

That painting, purchased in 1956, is estimated to fetch between US$6 million and US$9 million (C$7.5 million to C$11.3 million).

Mayer says the Chagall ended up on the auction block after more than 150 art museums across Canada were first offered the sale, and failed to respond.

He also says the gallery knows of a foreign museum that was "very interested" in purchasing "Saint Jerome," spurring it to act.

"We then understood that the risk to Canada of losing this national treasure was real, adding urgency to the matter. We began to explore other options, such as selling a high-valuation work of art," Mayer said Monday in a statement.

But at least two Quebec museums are also interested in the painting.

Stephan La Roche, director of the Musee de la civilisation in Quebec City, says his museum is working with the Montreal Museum of Fine Arts on a joint bid.

He says his museum has until June 11 to match or exceed the National Gallery's offer because they have right of first refusal.

"Saint Jerome" has been in Quebec City since about 1917 and was donated to the Cathedral-Basilica of Notre-Dame de Quebec in 1938. The painting was displayed in the cathedral until 1986.

The parish then entrusted it to the Musee de la civilisation where it remained in storage until the National Gallery requested to display it from 1995 to 2013, after which it returned to Quebec City.

La Roche says his museum is approaching patrons, seeking government grants, and is open to working with other partners, including the National Gallery, to buy the work. In that case, the painting would rotate between the institutions.

"It's a major piece in the history of art. There aren't many David paintings on the planet - there are a few at the Louvre, there are few in very large museum collections, there is only one in Quebec and it's that one," says La Roche.

"It's important to preserve it because no matter where it might be on the planet, that painting has a huge artistic value."

He says it's also important to keep "Saint Jerome" in Quebec because two French sisters brought it to the province with the rest of their art collection when they immigrated in the early 20th century.

La Roche says he would like to see their entire collection stay together in Quebec.

As for the owner, Monseigneur Denis Belanger says the parish offered "Saint Jerome" for sale in July 2016.

He says proceeds of the sale will create a fund in the sisters' names and that the interest will serve the parish "over the decades and over the centuries."

While Mayer says the Ottawa gallery touts several major French works from the 17th, 18th, 19th, 20th and 21st centuries, he says "a glaring exception is an important picture by David."

He adds that the gallery's board of trustees voted in December 2017 to sell the Chagall.

- With files from Cassandra Szklarski and Paola Loriggio in Toronto