The new director of the British Museum has said he will oversee “the most significant transformations, both architectural and intellectual” when he takes up the role in the summer.

Nicholas Cullinan, the outgoing National Portrait Gallery director, replaces former Victoria and Albert Museum head Sir Mark Jones, who was made interim director following the resignation of Hartwig Fischer over the thefts at the London-based institution.

Mr Cullinan’s appointment was announced on Thursday after it was approved by the board of trustees and Prime Minister Rishi Sunak.

He said: “One of the greatest museums in the world, it is an honour to become the next director of the British Museum.

“I look forward to joining its wonderful and dedicated staff and to work with its hugely impressive board in leading it into a new chapter.

“This will encompass the most significant transformations, both architectural and intellectual, happening in any museum globally, to continue making the British Museum the most engaged and collaborative it can be.”

He added that he wants to “pay tribute to my predecessors, most recently Sir Mark Jones, and look forward to building on their extraordinary achievements”.

Mr Cullinan faces an in-tray that includes the fallout from around 1,500 artefacts found to be missing, stolen or damaged at the museum, and overseeing its renovation.

He was appointed director of the National Portrait Gallery in April 2015 and has overseen the three-year refurbishment of the Trafalgar Square museum and its reopening.

Mr Cullinan invited his close friend US singer Courtney Love to DJ the opening and she most recently returned to play tracks at the National Portrait Gallery’s gala in March where she cosied up to him during the event.

The widow of Nirvana frontman Kurt Cobain called him her “soulmate” and her “family for life” in 2017 on Instagram and they attended the GQ Men of the Year Awards at the Tate Modern together that year.

Mr Cullinan previously worked at the Metropolitan Museum of Art in New York and the Tate Modern in London.

Museum chairman George Osborne said the trustees chose Mr Cullinan as he “brings proven leadership today and great potential for tomorrow”.

“He has shown his capacity as director of the National Portrait Gallery to oversee both a major physical renovation and a compelling renewal of purpose in a way that doesn’t take sides, but brings people together – and won universal acclaim,” Mr Osborne added.

“We believe he can achieve this, and more, on the bigger scale of the British Museum as we undertake a once-in-a-generation redevelopment. In doing so he can build on the solid foundations laid by Mark Jones, to whom we owe a huge debt of gratitude for stepping into the breach last year.

“I could not be more thrilled for Nick and more excited for us as we enter this new chapter in the long story of the British Museum with confidence, and back on the front foot.”

Art historian Mr Cullinan, who studied at the Courtauld Institute of Art in London, was awarded an OBE for services to the arts in the 2024 King’s New Years Honours list.

Culture Secretary Lucy Frazer said: “I look forward to Nick sharing his vision for the museum, including how he will strengthen its world-leading partnerships, deliver the next phase of its major capital project, and ensure the museum’s magnificent collections are enjoyed for generations to come.

“I want to thank Sir Mark Jones for his leadership and providing stability to the organisation during a difficult period.”

The new appointment also takes place amid controversy over several items in the British Museum’s collection.

The Parthenon sculptures from Greece, large stone statues from Easter Island, and the Benin Bronzes are among the disputed possessions.

Mr Osborne has previously said he was working on an exchange deal to allow the Parthenon sculptures, also known as the Elgin Marbles, to be displayed in Greece.

In January, the V&A and the British Museum agreed to a long-term loan commitment for Ghanian gold regalia to be displayed at the Manhyia Palace Museum in Kumasi.

Earlier in the week, the British Museum launched legal proceedings against former curator Dr Peter Higgs, who was dismissed in July last year for gross misconduct following allegations about items going missing from the collection.

At the High Court in London on Tuesday, Mrs Justice Heather Williams made an order saying Dr Higgs, who worked within the Department of Greece and Rome for more than 30 years, and who has been investigated by the Metropolitan Police but not charged, must list or return any stolen items within four weeks.

The court heard that Dr Higgs, who did not attend the hearing due to poor health, intends to dispute the claim.