Around 500 people are marching in central Madrid to support the Catalonia region's bid to hold a referendum on independence from Spain and criticizing the government for launching a crackdown to stop the vote.
On Sept. 20, Spanish police entered several Catalan government offices in Barcelona, seized documentation related to the referendum and arrested at least a dozen Catalan government officials.
The raids were part of a search for documents linked to a banned independence referendum planned for October 1st, a vote which the national government and Constitutional Court has deemed illegal, stating that only national authorities are able to call such votes.
They also sing the song dubbed Els Segadors (The Reapers in Catalan), which is the official anthem of the region and carry the Estelada flags, which are symbols of regional independence.
On Tuesday, Spain's Guardia Civil raided the offices of Unipost, a private delivery company, and seized more than 45,000 envelopes destined for households to notify them about the referendum, the Financial Times reported.
The province also has a foreign bureau in Barcelona, which is the capital and largest city in Catalonia.
In November 2014, a non-binding vote on independence for Catalonia showed 80 percent of people were in favor. Carles Puigdemont, head of Catalonia's pro-sovereignty government, accuses the Spanish government of trying to prevent a vote on independence, suspending their autonomy.
Cristobal Monotoro, Spain's Finance minister said, the national government would now set to take control of the Catalan region budget.
Spain's Interior Ministry says police have seized almost 10 million ballot papers that Catalan regional authorities planned to use in the October 1 independence referendum, which Spain says is illegal.
Many in Catalonia, which at various times during Spain's history has had a degree of self-government and now has a regional administration with limited powers, want it to be independent from Spain.
Catalonia has long sought independence from Spain, but the country's central government has repeatedly declined to grant the region independence, saying it would violate the country's constitution.
And a demonstration in support of Catalonia's pro-independence movement is to be held in Glasgow later.
The others work in various Catalan government departments, including its economic and budget affairs departments, a local Guardia Civil spokesman said.
Among those arrested in the operation that Spanish Prime Minister Mariano Rajoy said was "carried out on the decision of a judge in order to ensure the law was complied with" is Catalan Secretary for the Economy, Josep Maria Jove, who is Junqueras' assistant.
Sturgeon said the Edinburgh Agreement, drawn up by the Scottish and United Kingdom governments before the 2014 independence referendum in Scotland, could act as a template for others.