SPANISH police have reportedly detained a senior Catalan official and stormed government ministries involved in the banned independence vote.

The Guardia Civil entered offices of the Catalan region’s economy, interior, foreign affairs, welfare, telecommunications and tax departments, it has been reported.

Tensions with Madrid have been raised in the last few weeks as leaders in Catalonia vow to go ahead with an vote on splitting from Spain which the central government says is illegal and cannot take place.

It has been reported that 14 people have so far been arrested. One of them is Josep Maria Jové, secretary-general of the Catalan vice presidency.

Read more: Comparing Scotland and Catalonia's bid for independence

On Tuesday, the national police force seized over 45,000 envelopes packed in cardboard boxes that the Catalan government was ready to send to notify people around the region about the referendum.

One Catalonian official called for peaceful resistance to protect the buildings.

"The time has come - let's resist peacefully; let's come out and defend our institutions," the president of the Catalan National Assembly, Jordi Sánchez, tweeted.

The detained official's boss, Catalan Vice-President Oriol Junqueras, accused Spanish police of attacking the region's institutions and therefore its citizens too. "We will not allow it," he said.

Catalan police officers, on patrol outside the building in Terrassa, scuffled with pro-secession protesters trying to block the street outside.

The Catalan government is trying to organise the 1 October referendum, in the face of determined resistance by the national government to prevent it going ahead.

The Madrid government has been backed up by Spain's Constitutional Court, which suspended the referendum law passed by the Catalan parliament.

Days ago, more than 700 mayors from Catalonia met in a show of strength amid pressure from Spain's central government not to hold an independence referendum deemed illegal by the courts.

Hundreds of mayors stood on Saturday next to regional President Carles Puigdemont and Barcelona Mayor Ada Colau.

Mr Puigdemont thanked them for not backing down and insisted that most Catalans are determined to press ahead with the referendum despite the ban.