The Catalan president plans to address the region's parliament on Tuesday evening - with an expectation that he will say whether or not he is declaring independence from Spain.

The Spanish prime minister Mariano Rajoy has insisted Spain will not be divided should Catalonia declare independence.

Some separatist politicians say Carles Puigdemont has no other choice but to make a declaration of independence for the wealthy northeastern region, which has a population of 7.5 million people.

A disputed referendum on the issue earlier this month, which the government declared to be "illegal", saw more than 90% of Catalans vote in favour of secession.

Some ruling coalition members say any independence declaration could be simply "symbolic."

Spanish police violently cracked down on the referendum, using batons, shields and rubber bullets against peaceful voters and protesters.

Despite international condemnation about the state's use of force against Catalans, the Spanish government has issued stern statements warning against any further moves towards independence.

"If they declare independence, there will be decisions to restore the law and democracy," the deputy prime minister Soraya Saenz de Santamaria said in a radio interview on Monday.

She called for members of the Catalan government "who still respect democracy and freedom to refrain from jumping into the void."

"Credibility and dignity suggest making the declaration of independence tomorrow," said Jordi Sanchez, the head of the civil group National Catalonia Assembly.