A missing plaque marking the formal opening of a Belfast hospital building by Prince Andrew has prompted health officials to launch an investigation.
The display in Belfast City Hospital marking the opening of its tower block disappeared in January, with Belfast Trust saying it was removed without permission.
And now the trust has confirmed the removal of the plaque is the "subject of an active inquiry".
Read more: Prince Andrew loses honorary titles in NI
The Duke of York officially opened the Belfast City Hospital tower in June 1986.
A plaque marking the occasion was situated near the front entrance to the hospital. It read: "Belfast City Hospital tower opened by HRH the Prince Andrew, 25th June 1986."
Its removal came as Prince Andrew faced civil action in the US over sexual assault allegations, which he has repeatedly denied.
He was sued by Virginia Giuffre, who claims he abused her in 2001 when she was 17.
The case was settled out of court without Prince Andrew accepting liability, but he agreed to pay an unspecified amount to Ms Giuffre and to her charity for victims' rights.
Amid the controversy, the Duke of York's military titles and royal patronages were returned to the Queen.
Belfast Trust refused to release correspondence relating to the disappearance of the plaque following a Freedom of Information request.
It argued the material was exempt from disclosure due to ongoing investigations.
In a statement a trust spokesman said: "A plaque which was removed from the entrance of the Belfast City Hospital without direction from Belfast Trust remains missing and an investigation into its whereabouts continues."
The controversy surrounding Prince Andrew also led to Belfast councillors deciding to no longer fly the Union flag at city hall to mark his birthday.
It was agreed the flag would not be flown on February 19 but instead it would be raised on July 1 to mark the anniversary of the Battle of the Somme.
The Duke's birthday has since been removed from the UK's list of designated days for flying the Union flag on government buildings.
Belfast City Hall has flown the flag on designated says since a vote in December 2012 to end its permanent display.
The decision sparked weeks of street protests and disruption as loyalists clashed with police.
Read more: Belfast City Hall will not fly union flag for Prince Andrew birthday
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