Mariano Rajoy told Parliament the application of the Constitution's Article 155 was the "only possible" response to restore the region's legality, which he said has been liquidated by Catalan President Carles Puigdemont's push to secede.
Rajoy said he hopes the measures planned, including the sacking of Puigdemont's government and the curtailment of the Catalan parliament's powers, will be brief.
He said they should end with regional elections that he hopes could be held as soon as possible but only once law and order is restored.
Rajoy last weekend called for Article 155 to be implemented in an effort to stop a secessionist bid by the regional Catalan government following an outlawed October 1 referendum that Puigdemont said gave him the mandate to declare independence.
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Rajoy said the aim of Article 155 is not to suspend Catalonia's self-government but "to restore legality, boost the social co-existence that has been broken in Catalonia and tackle the economic consequences that its decisions are provoking."
The uncertainty over Catalonia's future could have an economic impact. Credit ratings agency DBRS warned today that the situation is hurting the region's economy and could become a drag on Spain's economy.
With Catalonia representing about one-fifth of Spain's annual gross domestic product, any slowdown in the region would affect the national economy.
The Spanish government has revised downwards its growth forecast for 2018 to 2.3 per cent from 2.6 per cent, largely because of doubts over Catalonia's future.
DBRS says the effects on the national economy will be "manageable," however, unless the crisis becomes protracted.