Basel's Fondation Beyeler says its has "no authority" to act after a work in its Paul Cezanne show was claimed to be stolen by the Nazis.

The watercolor, La Montagne Sainte Victoire, from around 1890 was included in its show which ended on Monday on loan from its anonymous owner.

Researcher Willi Korte says it was part of the collection of Gustav Schweitzer, a Jewish businessman who fled Berlin in 1935, until sometime in 1939 when it disappeared while he was in Paris.

Korte, who is working for Schweitzer's heirs, told The Art Newspaper that meant "it was either sold under duress after Schweitzer had fled Germany, or it was looted in Nazi-occupied territory" and Fondation Beyeler "should live up to its historical obligation to actively contribute to a fair and just solution".

A spokesperson for Fondation Beyeler said it would return the work to the lender who will be told about the claims, adding: "As a matter of principle, a Swiss museum has no authority to retain artworks without an appropriate legal basis."

The number of visitors allowed in Rome's Borghese Gallery, which is home to works by Caravaggio, Raphael and Titian, per hour. Plans to expand the building to allow more visitors were described as "blasphemy" by art historian Tomaso Montanari.

Vanessa Bell and Duncan Grant's art studio will be transported to London's Tate Britain and rebuilt there as part of a major exhibition about the couple.

More than 300 works will be on show in the exhibition tracking their emergence as part of the avant garde Bloomsbury Group in the early years of the 20th century.

The studio is from their home in East Sussex and is being relocated, while the house undergoes conservation work, for the show which runs from November 12 to April 11.

Also included will be works they made before they met as well as furniture and ceramics they designed and book cover designs made by Bell for her sister, the novelist Virginia Woolf.

1 - Audie Murray and Caroline Monnet are among the six shortlisted artists nominated for Canada's Sobey Art Award this year. The winner of the grand prize is announced on November 4 and gets $72,000 with the five other shortlisted artists receiving $18,000.

2 - A portrait by former US President George W Bush of his South Korean counterpart President Roh Moo-hyun has gone on public view for the first time. The painting is included in an exhibition about Roh's life which runs to September 27 in the South Korean town where he lived after his time in office.

3 - Painter Robert Wyland is preparing to take legal action after one of his Whaling Walls murals was painted over in Dallas to be replaced with another work celebrating this year's soccer World Cup. Wyland, who has painted more than 100 of the conservation-inspired murals around the world, told the Glasstire website he will sue whoever is responsible for commissioning the new work.

4 - More than 120 galleries have signed up to take part in London Gallery Weekend from June 5 to 7. Hayward Gallery director Sally Tallant is one of several cultural figures to have devised a curated route through the city for visitors to follow over the weekend.