Tens of thousands of people participated Wednesday in the traditional May Day parade in Cuba's capital as President Miguel Diaz-Canel and former head of state and current Cuban Communist Party (PCC) leader Raul Castro watched.

"Unity, Commitment and Victory" was the slogan printed on a large banner that led the enormous crowd of citizens of all ages and occupations through Havana.

The parade started a few minutes after 7:00 am at the iconic Plaza of the Revolution and was watched by the two leaders from the reviewing stand.

At the front of the parade packed with people, banners and signs were health-care workers, one of Cuba's main assets and a group that suffered a setback a few months ago when their contingent in Brazil had to return home following the election of far-right President Jair Bolsonaro.

In addition to the student, labor and social groups participating in the march, representatives of the LGBT community marched for the first time.

The group has achieved greater acceptance and visibility in the Caribbean country in recent years, in contrast to the harsh repression the community's members suffered decades ago.

Before the start of the parade, the classic speech delivered 19 years ago on May Day by late leader Fidel Castro was played for the crowd, an address in which he defines the concept of revolution and has become a kind of catechism for the people of Cuba.

In addition to Diaz-Canel and Raul Castro, high-level government officials, military commanders, PCC leaders and representatives from foreign countries, including several Russian Communist Party members, were on the reviewing stand.

The May Day celebration comes on the eve of the implementation of tighter sanctions by the United States, a decision that was repeatedly referred to and criticized by the state television anchors who covered the event live.

On April 17, President Donald Trump's national security adviser, John Bolton, said in a speech in Miami that the US government planned to strengthen the embargo on Cuba and further restrict travel and remittances to the communist-ruled island.

Bolton confirmed that starting on May 2 plaintiffs would be able to turn to the US courts to seek compensation from foreign companies with an economic presence in the US for properties confiscated in Cuba after the 1959 revolution and then used by those firms for business activities on the island.

The national security adviser also said that remittances sent by exiles or other family members to relatives in Cuba will be limited to $1,000 per quarter and that the US Treasury Department will also "restrict non-family travel to Cuba, or in other words, 'veiled tourism.'"

In the Plaza of the Revolution, chants were also heard in favor of Venezuelan President Nicolas Maduro's regime, Cuba's main partner and supporter in the region, which provides the island with approximately half of its oil at subsidized prices, and against alleged US interference in the South American country.

May Day parades were held in other cities across Cuba, including Santiago, where the second-largest parade took place, and in the central city of Villa Clara, where guerrilla leader Ernesto "Che" Guevara - who is buried there - was honored.