By Stephen Gibbs
BBC News, Havana
Cubans are being discouraged from mixing with tourists
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.
The new regulations make stark reading. Everyone who works in Cuba's expanding tourism industry - from bar staff to taxi drivers - is warned to keep a safe distance from foreigners.
Workers are advised that they can attend events at the homes of non-Cubans only with advanced written permission.
Gifts received from foreigners have to be declared. Electronic goods such as video players are expected to be handed over to the ministry for common use.
The rules have been approved by Cuba's new tourism minister, Manuel Marrero.
He is a colonel in the Cuban army and appears to have been charged with bringing discipline to the entire sector, but even he might find imposing these regulations a struggle.
Jobs in tourism are the most sought after in Cuba, precisely because they bring easy contact with foreigners and hard currency.
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.