Castro, 80, underwent intestinal surgery in late July, and handed over control of the communist Caribbean country - for the first time during his 47 years as leader - to his brother and potential successor Raul, 75. Speculation has since spread over whether Castro will return to power.
"[Fidel Castro's] rehabilitation is progressing satisfactorily," Jorge Martinez said at a meeting marking the 48th anniversary of the revolution that toppled the dictatorship of Fulgencio Batista in 1959.
Speaking at the ceremony, Russia's deputy foreign minister said Russia and Cuba had overcome a period of decline in their relations, and were reviving ties.
"The period of adaptation to the new reality was difficult, but we are rising to a new level of cooperation with our Cuban friends," Sergei Kislyak said.
The former Soviet Union for decades provided strong economic backing to the Latin American state, helping it survive more than 40 years of sanctions imposed by the United States, its Cold War foe, which sought to topple the Castro regime.
But the support was halted in the 1990s, when the Soviet empire collapsed and Moscow had to deal with an acute political and economic crisis at home.
Prime Minister Mikhail Fradkov visited Cuba last September, and reaffirmed that Russia would continue to press for the removal of the U.S. sanctions.
Fradkov said then Russia would provide Cuba with a 10-year $355-mln loan to be used to finance the delivery of Russian goods and services in 2006-2008.
The money will reportedly be used to modernize Cuba's energy sector and transport system, rebuild water conservation facilities and railroads, and design and deliver air navigation systems.
