A virtual political unknown when he was first elected to lead Catalonia in 2016, Carles Puigdemont became the face of the region's independence movement when he spearheaded a referendum the following year on breaking away from Spain.

The 58-year-old former journalist has lived in exile in Belgium since the 2017 vote, wanted by Spain accused of sedition.

He was arrested on arrival in the Italian island of Sardinia on Thursday and is expected to appear in court on Friday at a hearing that could see him extradited to Spain after four years as a fugitive.

Born in Amer, a small mountainous village of 2,200 people in Catalonia, the second of eight siblings, Puigdemont showed himself a staunch separatist at an early stage.

He never hid his breakaway tendencies, not even when he joined the conservative CDC party in 1980 at a time when it merely wanted to negotiate greater autonomy for Catalonia, rather than a full break from Spain.

"In Catalonia, many people became separatists in an allergic reaction to Madrid's policies. Not him, he always had these convictions," Antoni Puigverd, a poet and journalist who knew Puigdemont, said in 2019.

For 17 years, Puigdemont worked for the region's nationalist daily newspaper El Punt and was also mayor of the city of Girona, a separatist stronghold, from 2011 to 2016.

Puigdemont was a virtual political unknown when he was first elected to lead Catalonia in 2016 Puigdemont was a virtual political unknown when he was first elected to lead Catalonia in 2016 Photo: AFP / Tobias SCHWARZ

A father of two, Puigdemont was elected to the Catalan presidency in 2016 with a mandate to lead it to independence.

Unknown outside of self-rule circles, he was thrust into the global spotlight in October 2017 when his executive held an outlawed referendum on self-determination, marred by police violence, that was followed by a short-lived declaration of independence.

Madrid promptly sacked Puigdemont and his executive, dissolved the regional parliament, called snap local elections and imposed direct rule on the semi-autonomous, wealthy northeastern region.

The central government declared the result of the vote unlawful and Puigdemont was forced to flee to Belgium, where he has lived ever since to avoid prosecution.

"To all those who wanted to denigrate us, to silence us, I say to them that we will defend ourselves," he said while in exile.

Activists and Catalan "ministers" close to Puigdemont were arrested and sentenced to prison for sedition in 2019 during a trial held without him. Nine were pardoned in June by the government of current Prime Minister Pedro Sanchez.

Although sometimes labelled by his detractors as a "fugitive" or "coward", Puigdemont has continued to be involved in politics with his party Together for Catalonia, as well as being elected as an MEP in 2019.

His replacement as Catalan leader, Pere Aragones, is considered a more moderate pro-independence activist and his tenure has seen relations between Barcelona and Madrid become less fraught.