Huge demonstration against Catalan independence in Barcelona

Rajoy will not rule out suspending Catalonia's autonomy

France said it would not recognize Catalonia if the region declared independence.

The results of a banned independence referendum on October 1 "can not be an endorsement to proclaim independence but they constitute the possibility of opening a dialogue and worldwide mediation", she added.

The stakes are high for Spain as it faces its biggest political crisis since it became a democracy four decades ago.

Puigdemont is set to appear in the parliament of Catalonia on Tuesday after Monday meeting was suspended by the Spanish Constitutional Court.

Article 155 of Spain's constitution says that if a region's government breaches its constitutional obligations or "acts in a way that seriously threatens the general interest of Spain", Madrid can "take necessary measures to oblige it forcibly to comply or to protect said general interest".

Catalan authorities have stated they are open to dialogue with the Madrid government, something that has been rejected by those in the capital.

Highway management company Abertis and telecoms company Cellnex have joined a growing list of companies moving their headquarters elsewhere.

Abertis and Cellnex said they were pulling out for as long as there is uncertainty about the region's future.

And France said that Catalan independence would not receive global recognition.

Spain's deputy prime minister earlier warned of a tough response if Catalonia's political leader, Carlos Puigdemont, decides to announce a split from Spain.

Catalonia's sessionist leader Carles Puigdemont is expected to address the regional parliament on Tuesday and declare whether they will be separating itself from Spain or not.

Around 900 people were reportedly hurt when officers seized ballot boxes, fired rubber bullets and forcibly dragged people out of polling stations.

Hundreds of thousands of Spaniards rallied Sunday in a tide of red and yellow national flags in what is the worst upheaval since the country returned to democracy in the 1970s.

Around 350,000 people attended the rally, municipal police said, while organisers put turnout at between 930,000 and 950,000.

Puigdemont hinted in an interview on Sunday that the region would go ahead with the declaration if Madrid continued to refuse dialogue.

Spain's Prime Minister Mariano Rajoy could suspend the existing autonomous status that Catalonia enjoys under the country's system of regional governments.

The head of Spain's main opposition party, Socialist leader Pedro Sanchez, also called for Catalan leaders to drop an attempt to declare independence, saying "a universal declaration of independence doesn't have a place in a state ruled by law".