The £70 million relaunch of one of Scotland’s most prestigious museums has been rocked by claims that it may be showcasing even more Nazi-looted art than previously thought.

Two works in the priceless The Burrell Collection — donated to Glasgow in 1944 — are known to have been stolen from German Jews in the 1930s and the city’s council previously paid out thousands of pounds in compensation to their descendants.

But a new book, A Collector’s Life: William Burrell, by Glasgow Museums curator Martin Bellamy, reveals more treasures can now be traced to “forced sales” during Adolf Hitler’s rise to power.

Glasgow Life, the charity that manages The Burrell Collection, would not say what these items are but now accepts that the claim is accurate.

The refusal to identify the works was condemned by Scotland’s leading historian, Sir Tom Devine.

He said: “As long as the provenance of these items is established by experts and curators, it should always be made public.

“The question the public will ask is, ‘What do they have to hide?’

“I find the refusal rather curious. Curators of museums always want the truth to be out, and unvarnished at that.”

Controversial museum items taken from Jewish owners include an early 16th-century Swiss tapestry, The Visitation, and Still Life, a painting by Jean-Baptiste-Simeon Chardin. Glasgow Life has confirmed that while the tapestry is being held in storage, Chardin’s painting went on display on Tuesday.

Ephraim Borowski, of the Scottish Council of Jewish Communities, said: “I suggest that the point to be made is that this isn’t a question of law, but morals.

“Given the scale of the Holocaust, there may be no surviving family members to make a formal legal claim.

“It’s up to public galleries to acknowledge the dubious history of items in their collection.”

The results of the £70 million refurbishment programme were revealed on Tuesday, when the collection assembled by “millionaire magpie” Sir William Burrell opened its doors again for the first time in six years in Glasgow’s Pollok Park.

In their new book, Bellamy and co-author Isobel MacDonald reveal that wealthy shipowner Sir William, who died in 1958 aged 96, wrote frankly about the source of some of his purchases in small, soft-backed exercise jotters, which he used to record the provenance, description and price paid for each item.

The book adds: “Some of the practices that were employed would not be viewed as ethical today.”

Glasgow Life said in a statement: “There is nothing to suggest Sir William Burrell was made aware works he was buying originated from forced sales.”