Cuban President Miguel Diaz-Canel on Thursday rejected his country's inclusion in a US blacklist of the worst offenders of human trafficking.

The US State Department added Cuba to the lowest tier in its annual 2019 Trafficking in Persons (TIP) Report, alleging Havana's medical diplomacy, which sees Cuban doctors and healthcare workers assigned to work overseas, is a "modern form" of human trafficking. Cuban officials "force or coerce participation in these missions," the report said.

"More lies and slanders by US in ranking Cuba in the lowest tier of trafficking in persons report, attacking Cuban medical cooperation," Diaz-Canel said via Twitter.

Far from criminal, Cuba's unique program is an "example of solidarity, humanity and noble and legitimate collaboration between countries of the South," said the president.

"We denounce this immoral, lying and perverse accusation," he added.

Cuban Foreign Affairs Minister Bruno Rodriguez called the US decision "another baseless lie to justify new hostile measures" against the island.

The United States lacks the moral authority to evaluate or grade any country, especially in this matter, said Rodriguez.

"Cuba is distinguished for its zero tolerance policy and exemplary performance in preventing and fighting human trafficking with a low rate of this scourge," Rodriguez tweeted.

Over 8,000 Cuban medical workers in Brazil as part of a bilateral cooperation program were forced to leave the country late last year after Brazilian President Jair Bolsonaro accused the Cuban government of keeping most of the wages paid to the doctors, who he described as "slave labor."

In response, Cuba said Bolsonaro's statements were unacceptable.

Washington said in its annual report that Cuban doctors abroad are coerced by government officials to remain in such programs by withholding their passports, restricting their movement, using "minders" to monitor their movements outside of work, and threatening to revoke their medical licenses or retaliate against their family members in Cuba.

United States-Cuba ties have deteriorated since US President Donald Trump took office, dramatically reversing the normalization of relations begun by his predecessor Barack Obama.