His lawyer, Gonzalo Boye, told CNN the arrest was carried out on a Spanish Supreme Court warrant and a court spokeswoman said the Spanish court is contacting the Italian courts on Friday.
Puigdemont has been living in Belgium the past four years and faced arrest if he returned to Spain.
He went to Sardinia on Thursday to attend a cultural festival in an area where the historic Catalan language is spoken, a Catalan regional government official told CNN on Friday.
Separatist tensions continue in Barcelona and the surrounding northeast region of Catalonia. And the issue affects national politics right now, with the minority government of Spanish Prime Minister Pedro Sanchez relying on a Catalan pro-independence party, the Republican Left of Catalonia (ERC), for support on the upcoming budget and other issues. The ERC now heads Catalonia’s coalition government, partnered with Puigdemont’s Together for Catalonia (JxCat).
Spain’s government last June pardoned nine Catalan leaders, serving prison sentences, for their roles in the failed 2017 independence drive. Sanchez at the time said the move aimed to foster reconciliation between Catalonia and the rest of Spain.
But the pardons did not apply to Puigdemont, who fled in 2017 along with some top aides, after Madrid took temporary direct control of the region.