Deutsche Bank said on Wednesday damage claims filed by Italy's Monte dei Paschi di Siena over a derivative trade were "entirely without merit", vowing to defend itself vigorously.

A judicial source told Reuters last week the world's oldest bank was seeking at least 500 million euros in damages from Deutsche Bank and two former Monte dei Paschi executives over a loss-making 2008 trade known as "Santorini".

"We will defend ourselves vigorously against any claims for damages made by the client before the Tribunal of Florence," Deutsche Bank said in a statement.

(Reporting By Silvia Aloisi; Editing by Lisa Jucca)