Experts from Cuba and the US environmental protection agency met virtually on Wednesday to discuss the clean-up effort at the Matanzas supertanker port east of Havana in what the Cuban foreign ministry characterised as a “professional and fruitful exchange.”

Cuba asked for an assessment of its efforts so far and about gaining access to innovative US techniques and procedures from the EPA, other agencies and oil companies, the foreign ministry said.

A lightning strike ignited an oil storage tank at Matanzas three weeks ago, and the fire spread to three more tanks. It was extinguished after a week, and the government said it was the worst fire in the Caribbean island’s history.

The US considers Communist-run Cuba, just over 100 miles offshore, to be an enemy and has maintained a comprehensive sanctions regime on it since soon after former leader Fidel Castro’s 1959 revolution.

At the time of the fire, the US offered technical advice by phone.