What next in the Catalan crisis?

A Spanish judge on Friday issued an arrest warrant for Catalonia's deposed leader Carles Puigdemont over the region's contested quest for independence.

The legalities are likely to escalate tensions in Spain's worst political crisis in decades.

So what happens now? The following are the next key events in the crisis.

- Court probe and extradition -

Spain's National Court sent eight former officials in Puigdemont's government, including his deputy Oriol Junqueras, to jail pending a potential trial over their role in Catalonia's secession push.

A ninth former government official was allowed to leave custody on Friday after he posted bail of 50,000 euros ($75,000) pending a full trial.

But Puigdemont and four others refused to appear in court for questioning and a Spanish court issued warrants for their arrest.

The five, who are all thought to be in Belgium, can fight their extradition in the coming days. Meanwhile the National Court will continue its investigation.

The public prosecutor's office has asked that Puigdemont and the others be charged with rebellion, sedition and misuse of public funds.

The crime of rebellion carries a prison term of up to 30 years while sedition can be punished with a sentence of up to 15 years.

- Supreme Court hearing -

Spain's Supreme Court will on Thursday resume its hearings of six former members of Catalonia's dissolved parliament including speaker Carme Forcadell.

The hearings began on November 2 but were adjourned at the request of their lawyers. The six are also being investigated for their role in Catalonia's secession drive.

- Early vote preparations -

Spain's central government last month stripped Catalonia of its powers and called an early regional election for December 21 after the Catalan parliament voted to declare independence.

Parties that wish to stand together in a coalition in the polls must announce this by Tuesday.

During the last regional election in September 2015 Puigdemont's conservative PdeCat and the far-left ERC party stood together in a "Together for Yes" coalition.

The two sides have clashed in recent weeks over strategy but the decision to jail the bulk of the ousted Catalan government has rekindled feelings of unity.

The ERC party, which has long called for independence, is riding high in opinion polls and could prefer to run on is own, splitting the separatist camp.

Between November 13 and 18 Catalan parties must announce their list of candidates.

The tiny, anti-capitalist separatist Popular Unity Candidacy (CUP) party, a key ally of the "Together for Yes" coalition, must decide by this time if it will take part in the election called by the central government.

- Election campaign -

The election campaign officially kicks off on December 5 and runs until December 19.

Mass protests for and against independence are likely during the campaign, like the ones held in Barcelona throughout October.

- Elections -

During the last regional election, separatist parties won a slim majority of 72 seats in the 135-seat Catalan parliament for the first time.

While they captured just 47.8 percent of the vote, a quirk in Spanish election law gives a higher proportion of seats in rural areas where support for independence is higher.