BARCELONA/LA JONQUERA, Spain (Reuters) - Catalonia’s parliament pressed its case for secession from Spain on Tuesday, two days after a national election, while separatist protesters blocked one of the region’s major highways and also disrupted traffic in the Basque Country.

Protesters blocked the AP-7 highway in both directions around the secessionist Catalan stronghold of Girona.

Earlier, French riot police had used tear gas to clear protesters at the border who were blocking the AP-7 highway that links France and Spain. They arrested 18 people at the La Jonquera border crossing and Catalan police arrested one person, officials said.

Catalan demonstrators also converged on Tuesday on a highway in the Basque region near the French border town of Irun, disrupting traffic and causing jams of up to 11 kilometers (8 miles), the Basque transit authority said.

A secretive protest group called Democratic Tsunami has claimed responsibility for the disruption, which is aimed at drawing international attention to the Catalan independence drive.

In Barcelona local police tweeted that traffic had been disrupted at several major intersections, after another separatist group known as CDR called for protesters to block access points around the Catalan capital.

Defying a warning of legal consequences from Spain’s Constitutional Court, the Catalan parliament, which is dominated by pro-independence parties, approved a motion on Tuesday that expressed the “will to exercise the right of self-determination in a concrete way”.

The motion called for political action but is non-binding, a parliament spokeswoman told Reuters.

However, to avoid a dispute with Spain’s Constitutional Court, the chamber’s legal team decided not to publish the motion in the official parliamentary register even though it had been approved by lawmakers, a spokesman said.

Spain’s state prosecution office has asked Catalan prosecutors to investigate whether the parliament’s actions constitute a crime.

JAILED SEPARATISTS

The separatist protests, sometimes violent, have overshadowed Spain’s election campaign following the sentencing last month of nine Catalan separatist leaders who spearheaded a failed independence bid in 2017.

Spain’s far-right Vox party more than doubled its number of seats after its fiercely anti-separatist rhetoric struck a chord with many voters. Sunday’s vote produced a highly fragmented parliament, though the ruling Socialists and far-left Podemos party pledged on Tuesday to work together to try to form a majority coalition.

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The pro-independence cause received a tacit boost on Tuesday from an adviser to the European Court of Justice (ECJ).

Advocate General Maciej Szpunar said jailed Catalan separatist leader Oriol Junqueras, elected to the European Parliament while in detention, should have had the right to ask lawmakers to decide whether to uphold his immunity.

A Spanish government source said Szpunar’s conclusions were non-binding and that it was not possible to draw conclusions before the ECJ’s official ruling.

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But another former Catalan separatist leader who was also elected to the European Parliament in May, Carles Puigdemont, welcomed the adviser’s opinion.

“This shows another extremely serious injustice in which Junqueras is a victim; his rights and those of voters have been violated,” Puigdemont, who lives in self-imposed exile in Belgium, tweeted.

Junqueras, the Catalan government’s former deputy leader, was sentenced in October to 13 years in prison.

In June, 76 members of the European Parliament from a range of parties urged the assembly to protect the rights of Catalan leaders who were unable to collect their credentials, saying Madrid had violated their rights by barring them from taking their seats.