A visit to Cuba by US pop singer Beyonce and her rap star husband Jay-Z is coming under scrutiny in connection with the US economic embargo.
Two Republican members of Congress have requested official information on whether the couple had US government permission to travel there.
The stars caused a local sensation when they celebrated their fifth wedding anniversary in Havana this week.
There was no immediate comment from representatives of Beyonce.
A source familiar with the couple's itinerary told the Reuters news agency the trip was fully-licensed by the US treasury department as a "people-to-people" cultural visit that did not involve tourist activity, such as trips to the beach.
Ileana Ros-Lehtinen and Mario Diaz-Balart, both members of Congress from Florida, have asked the US treasury department to clarify what licence the two stars had obtained to travel to Cuba.
"Cuba's tourism industry is wholly state-controlled; therefore, US dollars spent on Cuban tourism directly fund the machinery of oppression that brutally represses the Cuban people," they wrote.
Beyonce and Jay-Z turned heads in the Cuban capital on Thursday when they toured the streets of Old Havana.
Visiting historical landmarks, they took photos and chatted to local residents.
Beyonce, a household name in her home country, sang the US national anthem at President Barack Obama's inauguration in January.
Americans are not allowed to visit Cuba and spend money there unless they have special US government permission, according to guidance on the US treasury website.