More than 100,000 workers in Cuba's tourism industry have been ordered to restrict their contact with foreigners to an absolute minimum.
New regulations from the communist state's tourism ministry apply to Cubans on the island and overseas.
They form part of a series of moves by the Cuban government to tighten state control across the country.
Workers are also told to watch their foreign employers and report actions that might threaten Cuba's revolution.
Fifty years of "revolution" and the failed state goes backwards to repression.
The rules are the latest of a series which have been passed by the Cuban government with the broad aim of recentralisation.
In the last few months, the US dollar has been removed from circulation. Private enterprise has been curbed and managers of Cuban state enterprises have been stripped of much of their autonomy.
President Fidel Castro has said that recentralisation is enabling the Cuban state to rise again, like a phoenix.