Spain's prime minister had demanded Catalan's leader clarifies whether independence has been declared.

Mariano Rajoy said clarification is needed before he can decide what steps to take, going on to say the Catalan government's response would be crucial in deciding "events over the coming days."

In a veiled threat, he said the clarity was required by the constitutional article that would allow Spain to intervene and take control of some or all of Catalonia's regional powers.

He said the government "wants to offer certainty to citizens" and it is "necessary to return tranquility and calm."

The Catalonia crisis explained in 60 seconds

Catalan regional president Carles Puigdemont said he would proceed with the secession but would suspend it for a few weeks in order to facilitate negotiations.

The Spanish government has given little indication it is willing to entertain the talks.

Opposition Socialist leader Pedro Sanchez said Spain's two main political parties agreed to renegotiate laws governing autonomy.

He said a deal was reached with Mr Rajoy to open talks in six months on reforming the constitution that would allow changes to the current setup governing Spain's 17 regions, including Catalonia.

Mr Sanchez said his party wanted the reform to "allow for Catalonia to remain a part of Spain," and that the socialists were backing Mr Rajoy's call for clarification from Mr Puigdemont.

Catalonia independence referendum: Riot police clash with voters Show all 17 1 /17 Catalonia independence referendum: Riot police clash with voters Catalonia independence referendum: Riot police clash with voters A man faces off Spanish Civil Guards outside a polling station in Sant Julia de Ramis Reuters Catalonia independence referendum: Riot police clash with voters Riot police form a security cordon around the Ramon Llull school in Barcelona EPA Catalonia independence referendum: Riot police clash with voters Riot police evict a young woman during clashes between people gathered outside the Ramon Llull school in Barcelona EPA Catalonia independence referendum: Riot police clash with voters Spanish Civil Guard officers break through a door at a polling station in Sant Julia de Ramis Reuters Catalonia independence referendum: Riot police clash with voters Spanish National Police clash with pro-referendum supporters in Barcelona on Sunday AP Catalonia independence referendum: Riot police clash with voters Crowds raise their arms up as police move in on members of the public gathered outside to prevent them from voting in the referendum at a polling station where the President Carles Puigdemunt will vote later today Getty Catalonia independence referendum: Riot police clash with voters People confront Spanish Civil Guard officers outside a polling station Reuters Catalonia independence referendum: Riot police clash with voters Three man hold each other as they try to block a Spanish police van from approaching a polling station AP Catalonia independence referendum: Riot police clash with voters A woman shows a ballot to a Spanish Civil Guard officer outside a polling station Reuters Catalonia independence referendum: Riot police clash with voters A man wearing a shirt with an Estelada (Catalan separatist flag) and holding carnations faces off with a Spanish Civil Guard officer Reuters Catalonia independence referendum: Riot police clash with voters Police try to control the area as people attempt to cast their ballot at a polling station in Barcelona Getty Catalonia independence referendum: Riot police clash with voters A man is grabbed by officers as police move in on the crowds Catalonia independence referendum: Riot police clash with voters Two women argue with a Spanish National policeman during clashes between Catalan pro-independence people and police forces at the Sant Julia de Ramis sports centre in Girona EPA Catalonia independence referendum: Riot police clash with voters Sant Julia De Ramis in Spain Getty Catalonia independence referendum: Riot police clash with voters Confrontation outside a polling station in Barcelona, where police have tried to stop people voting AFP/Getty Images Catalonia independence referendum: Riot police clash with voters A Spanish National Police officer aims a rubber-bullet rifle at pro-referendum supporters in Barcelona AP Catalonia independence referendum: Riot police clash with voters Riot police clashed with voters as polls opened in Barcelona Sky News

In a highly anticipated speech, Mr Puigdemont had said the landslide victory in the disputed referendum on 1 October gave his government in the regional capital, Barcelona, the grounds to implement its long-held desire to break its century-old ties with Spain.

But he proposed the regional parliament suspend the effects of the declaration to commence a dialogue and help reduce tension.

The central government in Madrid responded to say it did not accept the declaration and did not consider the referendum or its results to be valid.

Spain's deputy prime minister Soraya Saenz de Santamaria said the Catalan leader "doesn't know where he is, where he is going and with whom he wants to go".

She said Mr Puigdemont had put Catalonia "in the greatest level of uncertainty seen yet".

Article 155 of the constitution allows the central government to take some or total control of any of its 17 regions if they don't comply with their legal obligations.

Some 2.3 million Catalans — or 43 per cent of the electorate in the northeastern region — voted in the referendum. Regional authorities say 90 per cent were in favour and declared the results valid. Those who opposed the referendum had said they would boycott the vote.

Mr Rajoy's government had repeatedly refused to grant Catalonia permission to hold a referendum on the grounds that it was unconstitutional, since it would only poll a portion of Spain's 46 million residents.

Catalonia's separatist camp has grown in recent years, strengthened by Spain's recent economic crisis and by Madrid's rejection of attempts to increase self-rule in the region.