Catalan separatist leaders Carles Puigdemont and Antoni Comin received temporary accreditation as members of the European Parliament on Friday, a day after the European Union's highest court issued a ruling with favourable implications for them.

Previously unable to collect their credentials due to fears of being arrested by Spain, the two politicians, who live in self-imposed exile in Belgium, should get full accreditation in January at the earliest, a chamber's spokeswoman said.

The decision stems from Thursday's ruling by the Court of Justice of the European Union (CJEU) saying that imprisoned separatist leader Oriol Junqueras was entitled to immunity as an MEP after being elected in May.

Mr Puigdemont and Mr Comin also won European Parliament seats in May but fears of returning to Spain, where they face arrest warrants, prevented them from taking their oaths and collecting their MEP credentials.

"We are at the place where we should have been six months ago," Mr Puigdemont told reporters inside the European Parliament, where he and Comin collected their badges.

The former Catalan regional government president said he hoped to take part in the next parliamentary session and criticised the Spanish judiciary, which he said was not independent and could not guarantee the defence of their rights.