MADRID (AP) — The leader of the northeastern Spanish region of Catalonia reshuffled his Cabinet on Friday to strengthen the regional government, which wants to hold a referendum on independence from Spain promised for Oct. 1.

Spain's government says the vote is unconstitutional and has pledged to prosecute officials who take formal steps to hold it.

Catalan leader Carles Puigdemont told reporters that he is replacing three councilors in charge of security, presidency and education, as well as the Cabinet secretary, in order to "reinforce" the regional government.

The officials "took the decision of stepping aside," Puigdemont said.

Spanish media reported that the changes came following internal divisions about the feasibility of holding a referendum. Earlier this month, Puigdemont replaced another close aide who had voiced doubts publicly.

Spanish Prime Minister Mariano Rajoy called the changes "a purge" and "one more sign of the authoritarian drift" of Puigdemont's government.

"Today those in doubt are being purged in favor of radicalism," the conservative leader said. "What kind of dialogue do they seek with this behavior?"

Catalonia and Spain have been at loggerheads for years because of the regional government's plans to hold a secession vote. Spain's central government has challenged in the Constitutional Court nearly every measure taken by the Catalan government and has succeeded in blocking most of them.

The latest has been a draft law that would enable the ruling nationalist Catalan parties to declare independence from Spain within 48 hours of winning the referendum no matter what the turnout is for the vote.

The law was described by Rajoy as "authoritarian delirium." It needs to be approved by regional lawmakers first, before central authorities can challenge it through the Constitutional Court.

Catalonia, whose capital is Barcelona, represents a fifth of Spain's gross domestic product.

Polls consistently show the 7.5 million Catalans are evenly divided on independence, but a majority supports holding a referendum.