HAVANA - Cuba's newly found offshore oilfield was deemed inviable for exploration due to restricted access, said the country's state oil company on Monday.

Cubapetroleo (Cupet) said it "an active petroleum system" in the Gulf of Mexico, but the geology of the site made it impossible to exploit.

The rocks are very compact and prevent the ability to deliver significant quantities of oil and gas, said Cupet. "So the well cannot be qualified as a commercial discovery."

It is Cuba's second failed attempt to find commercially viable oilfield since the Italian-owned Scarabeo 9 oil rig was transported to the area in January.

In May, Spanish company Repsol reported that its offshore drilling north of Havana had failed and later announced it would stop exploration work in Cuban waters.

Cuba's 112,000-square-km territorial waters in the Gulf of Mexico are divided into 59 blocks, 22 of which have been contracted for exploratory drilling by companies from various countries.

Some foreign geologists estimate that the island country has offshore reserves of 5 billion to 9 billion barrels of crude oil, while Cuban experts believe there could be as much as 20 billion barrels.

But so far, all attempts to find a profitable oilfield in the gulf have failed.

Since 2007, Cuba produces about 4 million tons of crude and derivatives annually, enough to meet half of domestic demand. Venezuela supplies the remaining demand of about 100,000 barrels per day.