The Hermitage in St Petersburg, struggling to display or even catalogue its vast collection of art treasures, is to establish a satellite branch in Italy as its “window on the West”.

The treasures will be housed in the 14th-century Castello Estense, the “jewel” at the heart of Ferrara. A palazzo and park will also be restored to provide a residential study centre for Italian and Russian art experts.

“The Hermitage has three million items and even the Russians don’t know exactly what they’ve got,” said Gaetano Sateriale, the Mayor of Ferrara. “When I went to St Petersburg recently I was stunned to see whole rooms of Etruscan antiquities, far more than Italy itself has. They need our cataloguing skills.”

The move to set up Hermitage Italy confirms a trend, with some of the world’s great museums opening profitable branches abroad. It follows a decision by the Louvre in Paris to build an outpost in Abu Dhabi and to lend some of its 300,000 works of art — of which only a tenth are on display in Paris — to the High Museum of Art at Atlanta, Georgia.

French art critics have accused it of “cultural prostitution” — it will receive nearly $1 billion (£515 million) for the UAE deal and $6 million over three years from the US.

Officials in Ferrara insist that their agreement with the Hermitage is different. “The Louvre is opening commercial shop windows for the US and the Arab world,” Mr Sateriale told The Times. “Ours is not primarily a business deal, it is an artistic and scientific one based on Italian expertise and the reputation of Ferrara’s ancient university.

“We have 350,000 visitors a year and the Hermitage has 7 million. Obviously, we anticipate a jump to international status.”

Officials said that the annual running costs of the Hermitage’s Italian operation would be no more than €500,000 (£343,000) shared by Italy and Russia. The hope was that the new venture would pay for itself many times over.

Ferrara’s coup, signed by President Putin and Romano Prodi, the Italian Prime Minister, at a summit in Bari last week, follows three years of negotiations with Mikhail Piotrovsky, the Hermitage director. Ferrara was in competition with Mantua, once its rival as a Renaissance city state.

The city’s trump card was the restoration of the imposing, moated Castello Estense, which for decades was used as offices. It will stage its first Hermitage exhibition, featuring 16th-century paintings of the Ferrara school, in the autumn.

Contenders go on display next month in Palermo, in an exhibition from the Hermitage of 35 sculptures and paintings from the collection of Tsar Nicholas I, including Paris by Canova, Titian’s portrait of Pope Paul III and Andrea Vaccaro’s The Penitent Mary Magdalene.

The Hermitage already has “outposts” in Las Vegas, Amsterdam and London, with five rooms at Somerset House.

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