Four years after Catalonia's government staged a failed independence bid, former separatist leader Carles Puigdemont is arrested in Italy and may face extradition to Spain, where he is wanted on sedition charges.

Here are the key dates in the separatist crisis in the northeastern region of Spain.

Pro-referendum demonstrators gather in Barcelona to protest in September 2017 Pro-referendum demonstrators gather in Barcelona to protest in September 2017 Photo: AFP / PAU BARRENA

On September 6, 2017, Catalonia's parliament paves the way for an independence referendum on October 1, fiercely opposed by Madrid.

Security forces intervene in the referendum and images of police violence are beamed around the world.

On October 3, after hundreds of thousands of Catalans rally to protest the violence, King Felipe VI denounces the independence bid.

Spain's Pedro Sanchez, sitting on the left, speaks with Catalonia's regional leader Pere Aragones Spain's Pedro Sanchez, sitting on the left, speaks with Catalonia's regional leader Pere Aragones Photo: AFP / LLUIS GENE

On October 27, more than half of the Catalan parliament's lawmakers declare independence.

Madrid suspends Catalonia's autonomy, dissolving its parliament and dismissing its separatist leaders.

Catalan separatists demonstrate in the streets of Barcelona in September Catalan separatists demonstrate in the streets of Barcelona in September Photo: AFP / Josep LAGO

On November 2, eight regional ministers are detained. A European arrest warrant is issued for Puigdemont, who has fled to Brussels.

In a December 21 regional election, Catalans vote separatist parties back into power, including candidates in prison and self-imposed exile.

On June 2, 2018, Quim Torra becomes Catalonia's new president and the region's autonomy is restored.

Main dates in the ongoing legal saga of Catalan separatist leader Carles Puigdemont, as of his arrest in Italy Main dates in the ongoing legal saga of Catalan separatist leader Carles Puigdemont, as of his arrest in Italy Photo: AFP / Jorge MARTINEZ

That same day a new Spanish prime minister is also sworn in -- Pedro Sanchez, who adopts a softer tone on Catalonia but rules out any independence referendum.

Carles Puigdemont is arrested in Italy and may face extradition to Spain, where he is wanted on sedition charges Carles Puigdemont is arrested in Italy and may face extradition to Spain, where he is wanted on sedition charges Photo: AFP / HATIM KAGHAT

On October 14, 2019, the Supreme Court hands down prison sentences of between nine and 13 years to nine separatists, who are convicted of sedition.

Thousands of Catalans pour onto the streets in protest, blocking roads and rail tracks and storming Barcelona's airport, burning barricades and clashing with riot police.

Sanchez wins a second term in January 2020 with the support of Catalan separatist party ERC, who backs him in exchange for talks between Madrid and the Catalan government.

The talks begin on February 26 but are suspended due to the pandemic.

In September, Torra is banned from public office for refusing to remove separatist symbols from public buildings, triggering an early election in Catalonia.

During a February 2021 election, separatist parties increase their majority in Catalan parliament and agree to elect ERC moderate Pere Aragones as president.

He pledges to push for a new referendum on independence.

After an 18-month hiatus, talks resume in September, with Aragones saying that the two sides were still "very far apart".

In the name of "reconciliation", Sanchez says his government will pardon the nine jailed leaders.

On June 22, his cabinet approves the controversial move, despite fierce opposition from Spain's right-wing parties.

Puigdemont is arrested in Italy on September 23.

The European MEP, whose immunity was rescinded in March, will face a hearing that could see him extradited to Spain.