Two Italian climate change activists who glued themselves to the base of one of the Vatican Museums' most famous statues must pay almost £25,000 in damages and costs, a Vatican criminal court ruled on Monday.

Guido Viero and Laura Zorzini of the Ultima Generazione (Last Generation) group pulled the stunt against the Laocoon statue in August. The sculpture depicts a priest from Troy who tried to warn fellow citizens against taking in the Greeks' wooden horse.

The Tribunal of the Vatican City State, which has lay rather than religious judges, told Viero and Zorzini to jointly pay 28,148 euros (£23, 978) in damages to Vatican authorities, and 1,000 euros in legal costs, a court ruling showed.

They were also handed suspended jail sentences of nine months each, plus fines of around £1,284 each, also suspended. A third activist was given a suspended 120 euro penalty.

In a statement on Tuesday, Ultima Generazione said it would appeal, saying it was "disproportionate and unjust" to issue a punishment "for a few drops of glue" on a marble plinth that was added to the Laocoon in the 19th century.

Accusing the Vatican of hypocrisy, it said its activists had "simply wanted to turn the spotlight on what the Pope writes and preaches". Francis has recently called for "a rapid and equitable transition to end the era of fossil fuel".

The group has staged several high-profile protests in Italy, often targeting artworks or monuments. Last month, they poured diluted charcoal into Rome's iconic Trevi Fountain, turning its water black.