Mexican officials are evaluating how to send fuel to Cuba to help meet basic needs such as electricity and transportation without triggering reprisals from Washington, which has threatened tariffs against countries supplying fuel to the Caribbean island, four sources familiar with the matter said.

The sources said high-level Mexican officials have been talking to U.S. counterparts in order to gain clarity on the scope of the tariff threat outlined by President Donald Trump in an executive order and see whether there was a way to deliver the much-needed fuel. It remains uncertain whether Mexico will find a solution.

The White House referred Reuters to previous comments by Trump, who on Monday told reporters Mexico would stop sending oil to Cuba, without elaborating on why he believed that to be the case.

The U.S. State Department and the Mexican presidency did not immediately respond to requests for comment. Mexico's Foreign Ministry said it had no information on the matter.

Cuba needs to import fuel for two-thirds of its energy needs, and is struggling with worsening power outages and long lines at gas stations.

Shipments of Venezuelan oil to the island ceased following a U.S. blockade of Venezuelan tankers in December and the capture of President Nicolas Maduro in early January, leaving Mexico as Cuba's largest supplier.

However, in mid-January, the Mexican government halted shipments of crude and refined products amid pressure from the Trump administration. Washington subsequently threatened tariffs on countries that supply oil to the communist-ruled island, saying that Cuba poses an "extraordinary threat" to U.S. national security - a claim Havana denies.