The Spanish government has sent thousands of police officers to Catalonia in the run-up to Sunday’s planned referendum.
Spain’s central government insists the vote is illegal, and is determined to stop it from going ahead.
But Catalan officials say if the “yes” camp wins, they will declare independence within days.
With five days to go until the October 1 vote, the clash between Catalonia’s pro-separatist government and Madrid is increasingly being played out in the arena of logistics and international opinion.
During a joint news conference on Tuesday with Mariano Rajoy, Spain’s prime minister in Washington, DC, US President Donald Trump said it would be “foolish” for Catalonia not to stay in Spain.
Rajoy urged Catalan officials to return to “common sense” even as Madrid stepped up its effort to stop the vote from going ahead.