The Spanish Prime Minister says he will sack Catalonia's president and disband his cabinet if the Senate approves his request for special powers over the region.

Addressing the Senate chamber on Friday morning, Mariano Rajoy said the implementation of direct rule over Catalonia was in the best interests of the region's people, in the face of the worst constitutional crisis in Spain's recent history.

The Senate will vote later on whether to activate article 155, a constitutional clause which gives Madrid the authority to seize control of Catalonia's autonomous powers.

At the same time, Catalonia's regional parliament is also expected to hold a special session later in which a formal declaration of independence may be made.

The region's pro-independence parties submitted a motion at midday on Friday calling on the parliament to proclaim a republic of Catalonia, but it was unclear if that motion would be put to a vote.

That sense of uncertainty has run throughout the crisis since an illegal referendum on independence was held on 1 October, with both sides playing a game of political brinksmanship.

Mr Rajoy has cross-party support for imposing direct rule in the national parliament, and received rapturous applause both before and after his speech to the country's Senate today.

He said what was happening in Catalonia was "a clear violation of the laws, of democracy, of the rights of all, and that has consequences."

Mr Rajoy said the special measures of article 155 were the only way out of the crisis, and that Spain isn't trying to take away liberties from Catalans but instead protect them.

It will be the first time in four decades of democratic rule that the Madrid-based national government would directly run the affairs of one of Spain's 17 semi-autonomous regions, a move that will likely fan the flames of the Catalan revolt.

Mr Rajoy said the measures are aimed at restoring order and has promised to call a new regional election once that is achieved.

Carles Puigdemont, the Catalan president, scrapped hopes of a possible end to the political deadlock on Thursday when he opted not to call an early election himself and halt the drift toward independence.

The parliamentary sessions in Madrid and Barcelona are likely to last several hours before each votes on their resolutions.

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

Mr Rajoy's conservative Popular Party has an absolute majority in the Senate, thus guaranteeing the approval of his proposals. But he has also sought support from the country's main opposition parties. It will then be up to the government when to implement them.

Catalonia represents a fifth of Spain's gross domestic product. Polls show its 7.5 million inhabitants are roughly evenly divided over independence.