The US State Department says it supports the Spanish government's efforts to seize control of Catalonia after the region's parliament declared independence on Friday.

"Catalonia is an integral part of Spain, and the United States supports the Spanish government’s constitutional measures to keep Spain strong and united," Heather Nauert, the State Department spokesperson, said.

This echoes President Donald Trump, who said during a joint press conference with Spanish Prime Minister Mariano Rajoy in September that it would be "foolish" for Catalonia to secede.

"I think Spain is a great country, and it should remain united," Trump said.

The Catalan parliament voted 70 to 10 in favor of declaring the Catalan Republic "an independent, and sovereign, democratic and social state of law."