Barcelona, Spain - 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.
"You're talking about staying with a truly great, beautiful and very historic country," he said as Rajoy stood at his side.
Rajoy urged Catalan officials to return to "common sense" even as Madrid stepped up its effort to stop the vote from going ahead.
The chief prosecutor in Catalonia ordered police to seal off buildings that will house polling stations before the day of the referendum and deploy officers on the day of the vote to prevent ballots from being cast.
The move comes a day after he ordered regional police to identify those in charge of polling stations on Sunday, when the referendum is to be held.
"The order has been conveyed and it will be executed will all normality," a spokesman for Catalonia's regional police force, the Mossos d'Esquadra, told AFP.