The Caribbean island nation's communist authorities said Tuesday that from December 7 doctors will again be required to ask permission to travel abroad for private reasons.

"In the last three years, nearly half a million Cubans have traveled to other countries on personal business," the government reported, saying it represented an 81 percent surge over the prior three-year period. "In this context, migration of Cuban health professionals is a concern for the country."

Havana blames a US program that encourages Cuba's skilled medical workers to abandon posts abroad and emigrate to the United States for exacerbating a brain drain on the former Cold War adversary.

Inside Cuba, doctors and nurses complain that their profession has been devastated by an exodus of skilled personnel - with vital specialists now absent in many clinics and hospitals.

Reverses 2013 reform

A landmark emigration law passed in January 2013 allows Cubans to travel abroad without restrictions for the first time in half a century. And under Cold War-era US immigration law, Cubans who reach US territory are allowed to stay and are put on a fast-track to permanent residency.

Cuba might be impoverished, but it has long been known for producing quality medical professionals and providing excellent medical services. There are about 85,000 Cuban doctors with about 25,000 working in more than 50 countries.

Many Cuban doctors cite low salaries, poor working conditions and the possibility of well-paid jobs in other countries, especially the US, as their primary reasons for leaving.

But Havana laid the blame on Washington's permissive attitude to accepting Cuban nationals and sad the new restrictions will "mitigate damage occurring as a result of the United States' selective and politicized immigration policy towards Cuba and the unplanned departure of doctors to other countries."

Cubans leaving as US relations improve

Over the past two years, at least 100,000 Cubans have emigrated to the United States, the majority going overland from Ecuador. The pace has quickened dramatically this year, with many Cubans fearing that the detente announced nearly a year ago between the United States and Cuba will mean the end to special migration privileges.

A sudden spike in November led Nicaragua to seal its southern border with Costa Rica, where some 4,000 Cubans are stuck in harsh conditions. Another 850 are backed up in Panama, unable to cross into Costa Rica.

Ecuador has also announced visa requirements for Cubans, further complicating the overland journey that required many migrants to cross eight national borders illegally on their journey to the US.

jar/gsw (AP, Reuters, AFP)