Spanish Prime Minister Mariano Rajoy said Thursday that he will not allow the northeastern region of Catalonia to hold a referendum on sovereignty, adding that that is an initiative that is "radically contrary" to the constitution.

The head of the regional government, Artur Mas, on Thursday announced an agreement among Catalan nationalist parties to hold in November 2014 a referendum in which citizens would be asked if they want Catalonia to be a separate state and, if they vote yes, if they want it to be independent.

"With complete clarity, that consultation is not going to be held. It's unconstitutional and it's not going to be held," said Rajoy at a press conference held with visiting European Union President Herman van Rompuy.

The premier closed the door on any possibility that the consultation might take place, saying "I'm not going to authorize or to negotiate about something that is the property of all Spaniards," alluding to sovereignty.

He recalled that as prime minister he had sworn to fulfill the laws and the Constitution and holding a referendum on sovereignty in Catalonia would run counter to that.

Along that line, he issued a call to Mas to be responsible and fulfill his political commitment "not to violate the laws."

Van Rompuy, whose native Belgium suffers sharp regional and linguistic divisions, said that he had always been against separatism, noting that "it takes effort to remain united, but it's worth the trouble." EFE