The United States considers Catalonia an "integral part of Spain" and supports Madrid's measures to keep Spain "strong and united," the State Department said Friday after Catalan lawmakers voted to declare independence.

"The United States enjoys a great friendship and an enduring partnership with our NATO ally Spain," State Department spokeswoman Heather Nauert said in a statement.

"Catalonia is an integral part of Spain, and the United States supports the Spanish government's constitutional measures to keep Spain strong and united."

Nauert added that the United States and Spain "cooperate closely to advance our shared security and economic priorities."

Catalan lawmakers voted earlier to declare independence, as Madrid vowed in turn to "restore legality" and quash the region's secessionist bid.

The Catalan regional parliament in Barcelona passed a resolution to "declare Catalonia an independent state in the form of a republic."