A third crude tank caught fire and collapsed at Cuba's main oil terminal Matanzas, a local governor said on Monday, as an oil spill spread flames from a second tank that caught firetwo days earlier in the island's biggest oil industry accident in decades.

Cuba had made progress fighting off the raging flames during the weekend after drawing on help from Mexico and Venezuela, but late on Sunday the fire began spreading from the second tank, which collapsed, said Mario Sabines, governor of the Matanzas province, about 60 miles (130 klms) from Havana.

Matanzas is Cuba's largest port for receiving crude oil and fuel imports. Cuban heavy crude, as well as fuel oil and diesel stored in Matanzas, are mainly used to generate electricity on the island.

Sabines compared the situation to an "Olympic torch" going from one tank to the next, turning each into a "caldron" and now encompassing the area covering three tanks and with flames and billowing black smoke making tackling the situation "complicated".

Cuban state-run television has covered the unfolding disaster live since Saturday and President Miguel Diaz-Canel has been a constant presence there, highlighting the economic and political importance of the situation.

The Communist-run and heavily U.S. sanctioned country is all but bankrupt and blackouts, gas and other shortages already had created a tense situation with scattered local protests following last Summers historic unrest in July.

Residents expressed fear that the crisis will worsen as the hottest months of the year bear down.

"Oh my God, no lights and no gas, that is what this means," Havana resident Pia Ferrer exclaimed in an upscale neighborhood of Havana.