Pro-independence activists in Spain’s autonomous region of Catalonia have planned a massive rally ahead of a significant regional poll.

According to reports, a large demonstration is to be held in Catalonia’s regional capital city of Barcelona on Friday to mark the region’s “National Day” and also back Catalonia’s secession from Spain.

The rally is deemed to be of great importance as it can turn into a power parade for pro-secession parties, which are expected to win the majority of seats in the region’s parliament in the upcoming elections due to be held on September 27.

President of Catalonia’s regional government Artur Mas has vowed to intensify efforts for Catalonia’s independence if pro-secession parties, including the nationalist CDC, left-wing separatist ERC and anti-capitalist CUP, emerge triumphant in the polls.

Meanwhile, Catalan National Assembly President Jordi Sanchez called for a massive turnout in the Friday demo, saying the potential establishment of the Catalan Republic will mark “the beginning of a new country where all social groups have their say.”

Sanchez, however, stressed that the "National Day" should not turn into an electoral event in the hands of political parties, adding, “Everyone who believes in the right to decide and the need to push for a new country will have a place there.”

This is while the non-nationalist Ciutadans party described the scheduled rally as “partisan,” saying it only “interests a few” and will cause a “split” in the Catalan society.

We will “put all the possible obstacles” to prevent the event from happening, said Carina Mejías, a senior member of Ciutadans.

The Catalan president staged a symbolic independence referendum in November 2014 after the government in Madrid used the courts to block his bid to hold an official referendum.

Nearly 80 percent of the 2.2 million people who took part in the vote backed secession, though the turnout was little more than 40 percent.