A search and rescue operation is underway in the Caribbean for two missing sailboats filled with humanitarian supplies travelling from Mexico to Cuba.

Mexico has deployed naval teams and military search aircraft to locate the Friendship and Tigger Moth, which were carrying at least nine crew members, the Mexican navy said in a statement.

The vessels had been expected to arrive in Havana on Tuesday or Wednesday, but there has been no communication from them and no confirmation of their arrival, the navy said.

The Mexican navy stated it is committed to using all resources at its disposal to locate the boats and ensure the safety of the crews.

The two missing ships departed Isla Mujeres, in the Mexican state of Quintana Roo on March 20.

The nine crew members are from Poland, France, Cuba, and the U.S. Mexico established contact with maritime rescue coordination centres from each respective country along with their diplomatic representatives.

The captains and crews are experienced sailors, and both vessels are equipped with appropriate safety systems and signalling equipment, according to a spokesperson from the convoy.

No comments have been made regarding the missing boats by the Cuban government. Earlier in the week, Cuba welcomed another boat that had successfully delivered humanitarian aid.

Volunteers and NGOs have been essential in facilitating humanitarian aid to Cuba since January when the U.S. imposed a fuel embargo on the island.

The United Nations has raised concerns over significant supply shortages in Cuba, where more than 50,000 surgeries have been cancelled amid electricity supply constraints.

Cuba's dependence on humanitarian shipments from Mexico has escalated during the country’s ongoing energy crisis.

The U.S. has exerted increased pressure on Cuba, following the seizure of former Venezuelan President Nicolás Maduro, which previously aided Cuba with substantial oil supplies.