The streets of Barcelona have been flooded with demonstrators numbering up to 200,000 who are demanding the release of two jailed Catalan leaders who have been in police custody without bail pending an investigation for alleged sedition.
"They want us to be afraid so we stop thinking of independence, but the opposite will happen". We have demonstrated in Catalonia that citizenship is far greater than any idea.
"The Prime Minister reiterated that the United Kingdom is clear that the referendum had no legal basis and that any unilateral declaration of independence would be inconsistent with the rule of law", a spokesman for May said following her phone call with Spanish Prime Minister Mariano Rajoy. "We hope they will be released soon", he said.
Catalan President Carles Puigdemont made an ambiguous statement about the region's future last week, saying he has the mandate to declare independence but adding that he would not immediately move to implement it in order to allow time for talks with the central government.
Unless he backs down, Deputy Prime Minister Soraya Saenz de Santamaria said Madrid would trigger article 155 of Spain's constitution, a never before used measure that could allow it to take direct control over semi-autonomous Catalonia.
The referendum, marred by a police crackdown on voters, resulted in a 90-per cent "Yes" vote.
Spain's top court has ruled that the referendum was unconstitutional, adding legal weight to the government's efforts to block an attempt by the region to break away from Spain.
The standoff has sparked a business exodus, with almost 700 companies moving their legal headquarters out of Catalonia in a bid to minimise the instability.
The Spanish league have delayed putting out to tender their global television rights amid uncertainty over what the Catalonia crisis could mean for Barcelona, La Liga president Javier Tebas said on Tuesday.
Sturgeon, leader of the pro-independence Scottish National Party, has called for dialogue between the two sides and to find a way forward "that respects the rule of law".
The groups count tens of thousands of members each and have emerged as influential players in the crisis.
Meanwhile, Agusti Alcoberro, who is standing in for Sanchez as head of the Catalan national assembly, said peaceful protests would be the local response to what he said was the Spanish government's heavy-handed approach.
Participants in the Tuesday protest chanted, "Political prisoners, freedom". She understands Spanish but insisted on speaking to AFP in Catalan, remembering the times during Francisco Franco's dictatorship when the regional language was officially banned and she "had to pay one peseta for every word of Catalan spoken at school".
Supporters of secession maintain that the yes vote won and that Catalan officials have a mandate to declare independence.