The Mexican Navy activated search and rescue efforts in the Caribbean on Thursday, in hopes to locate two missing sailboats which were carrying humanitarian aid to crisis-hit Cuba.

The boats left Isla Mujeres, in the Mexican state of Quintana Roo, last week and were bound for Havana.

With nine people of different nationalities on board, the boats did not arrive in the Cuban capital on March 24 and March 25, as scheduled.

In a statement, the Navy appealed to seafarers and maritime authorities in the region to report any information or sightings. It said it was also using an aircraft to search the route between Isla Mujeres and Havana. 

Why were the boats sailing to Havana?

The aid-carrying boats were part of efforts to provide relief to Cuba as it faces a severe energy and economic crisis due to a tightened US embargo on oil and other goods.

The Trump administration has tightened its blockade on Cube in January following the capture and deposing of Venezuela's President Nicolas Maduro.

Volunteers in Mexico, last week, loaded boats with essentials like rice, beans, baby formula, wipes, and medicine as they prepared to set sail to Cuba. The vessels were a part of the "Nuestra America Convoy," a non-government initiative to deliver vital supplies to the struggling country.

One separate vessel from the convoy reached Havana on Tuesday.

"The captains and crews are experienced sailors, and both vessels ​are equipped with ‌appropriate safety systems and signalling equipment," a spokesperson for the convoy said in a statement to Reuters.

"We are cooperating ​fully with the authorities ⁠and remain confident in the crews' ability to reach Havana safely."

Mexican authorities contacted maritime rescue coordination centers in several countries including Poland, France, Cuba and the US, the Navy said. They also contacted diplomatic representatives of the missing individuals' countries of origin, which have yet to be disclosed. 

Edited by: Rana Taha