Puigdemont is wanted in Spain on allegations of sedition over his attempts to have Catalonia break away from Madrid through the 2017 referendum
Exiled former Catalan president Carles Puigdemont was awaiting a court hearing in Italy on Friday after being arrested four years after fleeing Spain in the aftermath of an independence referendum that Madrid ruled illegal.
The European MEP -- who has been based in Belgium since the 2017 referendum -- was detained in the Sardinian town of Alghero on Thursday, his chief of staff Josep Lluis Alay said.
"He'll appear before the judges of the court of appeal of Sassari, who will decide whether to let him go or extradite him" to Spain, where he faces charges of sedition, he announced on Twitter.
Puigdemont's Brussels-based lawyer, Gonzalo Boye, told AFP on Friday his client had spent the night in a jail cell and was waiting for news of the preliminary hearing.
"We don't know if it's today or tomorrow," he said, an assessment confirmed by an Italian lawyer helping Puigdemont in Sardinia, Agostinangelo Marras.
Supporters had already gathered outside the court in Sassari, a city in the north-west of Sardinia, with one holding aloft a large Catalan flag. One banner called for freedom for "Catalan political prisoners."
Boye had previously said Puigdemont was arrested as he arrived in Italy for a cultural festival he was attending in his capacity as an MEP. The town of Alghero has strong Catalan links.
Boye said the arrest was made on the basis of a warrant issued in October 2019 that had since been suspended.
Puigdemont, 58, is wanted in Spain on allegations of sedition over his attempts to have Catalonia break away from Madrid through the 2017 referendum.
His arrest comes a week after the left-leaning Spanish government and regional Catalan authorities resumed negotiations to find a solution to Spain's worst political crisis in decades.
In March, the European Parliament rescinded immunity for Puigdemont and two other pro-independence MEPs, a decision that was upheld in July by the EU's General Court.
However, the European Parliament's decision is under appeal and a final ruling by the EU court has yet to be made.
Following Thursday's arrest, Madrid expressed "its respect for the decisions of the Italian authorities and courts."
"The arrest of Mr Puigdemont corresponds to an ongoing judicial procedure that applies to any EU citizen who has to answer to the courts," the Spanish government said in a statement.
It added Puigdemont should "submit to the action of justice like any other citizen."
New Catalan president Pere Aragones -- a separatist but more moderate than his predecessor -- strongly condemned the arrest.
"In the face of persecution and judicial repression, the strongest condemnation. It has to stop," he wrote on Twitter.
He added that "self-determination" was the "only solution."
Quim Torra, who took over the presidency in 2018 following the referendum, described Puigdemont's possible extradition to Spain as "catastrophic" and called on pro-independence activists to be "on high alert."
Meanwhile, supporters starting sharing hashtags such as #FreePuigdemont, as the Catalan National Assembly urged people to protest against his "illegal detention."
In Barcelona, several hundred demonstrators gathered outside the Italian consulate, some holding makeshift signs reading "Freedom" in Catalan over Puigdemont's picture.
Others shouted "Free our president" in Italian and waved Catalan independence flags.
Besides Puigdemont, former Catalan regional ministers Toni Comin and Clara Ponsati are also wanted in Spain on allegations of sedition.
The October 2017 referendum was held by Catalonia's separatist regional leadership despite a ban by Madrid and the process was marred by police violence.
A few weeks later, the leadership made a short-lived declaration of independence, prompting Puigdemont to flee abroad.
Others who stayed in Spain were arrested and tried.
However, Puigdemont did not benefit from the pardon granted in June to nine pro-independence activists who had been imprisoned in Spain.