Cuban electrical and petroleum workers have marched in Havana to celebrate International Workers’ Day, or May Day, as the government pledges to stand firm against growing US pressure which is further straining the economy.

Ninety-four-year-old former leader Raul Castro and President Miguel Diaz-Canel took part in the celebrations in the capital on Friday, while the administration of US President Donald Trump announced further sanctions.

A White House statement said the sanctions would target those involved in the security services, along with “material supporters of the Cuban government”. The statement added, without evidence, that the Caribbean island serves as a “safe haven for transnational terrorist groups” such as the Lebanese armed group Hezbollah.

A US energy blockade has already battered the country’s struggling economy and contributed to widespread energy blackouts.

“We are living through difficult times,” said Yunier Merino Reyes, an accountant with the Electric Union who joined Friday’s march to celebrate his colleagues. “We are carrying out a very tough, arduous and relentless effort — day and night — to provide electricity to the people who need it,” he told the Associated Press.

The Trump administration has frequently threatened Cuba with military attacks in addition to greater economic pressure.

“Today Cuba demonstrated once again that this people does not give up, and that we will defend our homeland tooth and nail, even though we want peace,” Milagros Morales, a 34-year-old Havana resident who took part in the march, told Reuters.