BARCELONA — The escalating confrontation over Catalonia’s independence drive took its most serious turn on Saturday as Prime Minister Mariano Rajoy of Spain announced he would remove the leadership of the restive region and initiate a process of direct rule by the central government in Madrid.

It was the first time that Spain’s government had moved to strip the autonomy of one of its 17 regions, and the first time that a leader had invoked Article 155 of the Spanish Constitution — a broad tool intended to protect the “general interests” of the nation.

The unexpectedly forceful moves by Mr. Rajoy, made after an emergency cabinet meeting, thrust Spain into uncharted waters. The prime minister is trying to put down one of the gravest constitutional crises his country has faced since embracing democracy after the death of its dictator Gen. Francisco Franco in 1975.

The steps were immediately condemned by Catalan leaders and risked further inflaming an already volatile atmosphere in the prosperous northeastern region. On Oct. 1, thousands braved national police wielding truncheons to vote in a contentious independence referendum for Catalonia, even after it was declared illegal by the Spanish government and courts.

