Cuban state media say Communist Party leader Raul Castro is recovering from a hernia operation.
State television said on its evening broadcast that the 86-year-old leader who stepped down as president last month was following Friday's plane crash in Havana as he recovered from surgery.
The report offered no further details on Castro's health.
State media also said Cuba would fly flags at half-staff during an official period of mourning lasting until Sunday night.
Argentina's Foreign Ministry says two of the South American nation's citizens died in Friday's crash of a passenger jet in Cuba.
A ministry statement says Argentina is "deeply shaken" by the deaths.
The flight operated by Cuban state-run airline Cubana de Aviacion had at least 110 people on board when it crashed near the Havana airport shortly after takeoff.
Cubana had hired the aircraft from Mexican charter company Global Air.
Authorities have not given an official death toll, but so far only three people are said to have survived.
Cuban Communist Party newspaper Granma says the passengers were mostly Cubans plus five foreigners. A six-person Mexican crew was also on board.