Thieves have stolen almost 50 pieces of gold jewellery by the Italian sculptor Umberto Mastroianni worth 1.2 million euros in a targeted hit on an exhibition in northern Italy, curators said Saturday.

A "highly specialised gang" made off Wednesday night with almost the entire collection of rings, bracelets, pendants and sculptures by Mastroianni, considered one of Italy's greatest contemporary sculptors, on display at the Vittoriale degli Italiani estate on Lake Garda.

Only one of the 49 items in the collection, worth a total of 1,207,400 euros (around $1.3 million), was recovered elsewhere on the estate, the Vittoriale said in a statement after holding a press conference on the theft.

"These exceptional artefacts, true 'wearable sculptures', represent the most important testimony of the master's gold production," said Lorenzo Zichichi, president of the Centre for Studies of the Works of Umberto Mastroianni.

If the pieces are not recovered, the theft -- almost the entire collection of Mastroianni's gold, which belonged to his relatives -- would represent an "inestimable loss", Zichichi said.

  Targeted hit 

 The exhibition, entitled "Like a warm and fluid gold. The golds of Umberto Mastroianni", opened in December at the Museo d’Annunzio Segreto and was due to close on Friday.

The works were designed and forged by Mastroianni -- known also for his huge monuments -- from the 1950s until his death in 1998.

"Of the 49 works subject to the theft... only one, entitled "Man/Woman", was later found inside the complex", the Vittoriale said, without providing further details.

The head of the Vittoriale, Giordano Bruno Guerri, said he could not go into details of the robbery, which was under investigation by police and art specialists.

"But we can say that our alarm systems are very extensive and already of the highest level, we were evidently hit by a highly specialised gang," Guerri said.

He noted that other jewels next to the Mastroianni pieces were "not even touched".

Mastroianni was born in the town of Fontana Liri, south of Rome, in 1910.

His works include monuments in several Italian towns honouring the World War II resistance movement. He donated 27 of his sculptures to the state in 1987.

The Vittoriale is an estate built by Gabriele D'Annunzio, the Italian writer and politician, World War I hero and early supporter of fascism. It is now a national monument, run by a foundation.