Just weeks ahead of a regional independence referendum, nearly one million Catalans staged a massive rally in Barcelona to support the independence vote from Madrid.

On Catalonia's national day, the ‘Diada’, nearly one million people marched to support the upcoming independence referendum planned for October 1, police said on Twitter.

Al voltant d'un milió de persones han participat a la manifestació de la #Diada2017 a Barcelona — Guàrdia Urbana BCN (@barcelona_GUB) September 11, 2017

The rally marked the anniversary of the loss of Catalan independence to Spain in 1714 when Barcelona was captured by troops of Philip V of Spain. Over three hundred years later waving red and yellow striped flags, Catalonians poured onto the streets of their regional capital demanding the return of their autonomy.

Chanting pro-independence slogans, the crowd carried massive 'Si' banners to convince people to vote ‘Yes’ in the planned referendum despite objections from the central government in Madrid.

READ MORE: Catalonia sets independence referendum date, Spain seeks to press criminal charges

Fearing the possible breakaway of Catalonia, the country's Constitutional Court last Thursday suspended the regional referendum following a legal challenge by Prime Minister Mariano Rajoy. Since then, authorities have initiated a number of searches at regional newspaper offices and have raided printing shops that, according to reports, were aiding in the preparation of the referendum.

Goosebumps. 1 million of catalans sing along together the Catalonia's anthem. 😍 #Diada2017pic.twitter.com/5GN7iyWXde — Carlos 🇪🇺 #Sí 🗳 (@CarlosRivasFdez) September 11, 2017

Despite heavy pressure from Madrid, the regional authorities still plan to hold the vote.

“It’s not an option that the referendum won’t go ahead. It’s 20 days away and we’ve already overcome many hurdles,” head of Catalonia’s regional government, Carles Puigdemont, told journalists Monday.

Another remarkable #DiadadeCatalunya. Third one for me personally. In 20 days Catalans will vote. #Diada2017pic.twitter.com/O3jbBuQYdh — Janne Riitakorpi (@JanneRiitakorpi) September 11, 2017

The pro-independence bloc has argued that full sovereignty would benefit Catalonia, especially amid the high unemployment rate and austerity measures that came as a result of Spain's financial crisis, Jonathan Shafi, chairman of Radical Independence Campaign (RIC), told RT.

“The root cause is the economic crisis of 2008. It is the austerity measures we’ve seen take place. What is happening is that people are looking to have more control over their lives, they are looking for much more in terms of a saying of how their lives are run," Shafi told RT.

The 2014 independence referendum in Catalonia was thwarted by the Spanish Constitutional Court which declared it illegal. Three years ago, some 80 percent voted to split from Spain, although the symbolic vote had a poor turnout with only about a third of the region’s voters turning up at the polls.

Separatist sentiment in Catalonia traditionally runs high, and from time to time becomes the driving force behind massive pro-independence rallies attended by tens of thousands of people. While some gatherings have turned rowdy in the past, Monday’s rally passed without major incidents authorities said.

Cap incident destacable a la concentració de la #Diada2017. Gràcies per la col·laboració i civisme de tots els participants en el dia d'avui — Mossos (@mossos) September 11, 2017

Despite a strong turnaround at rallies, only 650 municipalities where roughly 40 percent of the region’s population reside, have agreed to participate in the referendum which is scheduled to take place in less than three weeks.

A recent poll conducted by El Espanol suggests 50.1 percent of roughly 7.5 million people living in Catalonia were in favor of independence. Some 45.7 percent reject autonomy for Catalonia while 4.2 percent preferred not to answer.