Rome (dpa) - A painting recovered by chance in December in the northern Italian city of Piacenza is a Gustav Klimt painting that had gone missing 23 years ago, experts confirmed on Friday.

The work, "Portrait of a Lady," was found on December 10 in the courtyard of the Ricci Oddi Modern Art Gallery, from where it was stolen in 1997.

Gardeners pruning vegetation found it inside a cavity protected by a metal door and hidden by thick layers of ivy. It was wrapped in a black plastic bag and appeared undamaged.

The experts' findings were presented in a press conference organized by police and streamed online by local newspaper PiacenzaSera.it.

"I can finally announce to all the people of Piacenza, to all experts, to all of our friends, that the work [...] is AUTHENTIC!," Laura Bonfanti, vice president of the Ricci Oddi gallery, tweeted.

Klimt, an Austrian art nouveau master, lived from 1862 to 1918. The recovered painting is one of a series of portraits of women he painted in the last years of his life, between 1916 and 1918.