The European Parliament is begun looking into — at the request of the Spanish authorities — the possibility of lifting the parliamentary immunity of self-exiled MEP Carles Puigdemont.

Puigdemont fled in 2017 after Spain issued a warrant to arrest him for his part in what Madrid deemed an illegal Catalan independence referendum.

He is now based in Belgium and became an MEP last May. He wants to return to Spain next month to visit jailed ex-leaders of Catalonia.

"The Spanish authorities have asked the president [of the European Parliament] to lift the immunity of Carles Puigdemont and Toni Comin to continue the judicial proceedings against the two MEPs," said Ewa Bozena Kopacz, vice president of the European Parliament. "In compliance with parliamentary rules, this demand was put to the judicial affairs commission."

The decision is expected to take several months.

The immunity of MEPs is not a "personal privilege" but "guarantees that MEPs can exercise their mandate without being threatened by arbitrary or political proceedings", according to the European Parliament.

Spain has issued an arrest warrant for Puigdemont for "secession" and "public fund embezzlement" after the former Catalan cabinet's unsuccessful independence bid in 2017. Puigdemont alongside Cominleft Spain and are both now MEPs.

Puigdemont took his seat as a member of the European Parliament on Monday, following a ruling from the EU's top court which allowed him to do so. The former Catalan leader has said he trusts that his immunity as MEP will protect him.

If Puigdemont's parliamentary immunity is lifted, it will be up to Spain to decide whether to annul his mandate as MEP.