The parliament of Spain's Catalonia region is set to elect a new leader this week, although the event may be upstaged by the return of its former leader from self-imposed exile, despite a pending warrant for his arrest.

Carles Puigdemont is the figurehead of hardline separatist party Junts, and led Catalonia between 2016 and 2017 before fleeing Spain following a referendum on independence deemed illegal by the judiciary.

It remains unclear how he plans to return to the country and enter the regional parliament while evading police.

Jordi Turull, secretary-general of Junts, told broadcaster 324 on Tuesday that he would call for the leadership vote to be suspended if Puigdemont is detained, as "it cannot take place in normal conditions" without him present.

The vote to invest Socialist Salvador Illa, who will be backed by the left-wing separatist ERC party after a bilateral deal last week, will kick off on Thursday at 10 a.m. local time (0800 GMT), according to the parliamentary speaker.