Researchers have discovered a gigantic complex of 200 million termite mounds in north-eastern Brazil, which may be up to 4,000 years old and covers an area about the size of Great Britain.

Although visible on Google Earth, the conical mounds, some of which rise up to 10 feet high, are largely hidden from view at ground level in semi-arid, thorny-scrub forests, according to research published this month in Current Biology.

"These mounds were formed by a single termite species that excavated a massive network of tunnels to allow them to access dead leaves to eat safely and directly from the forest floor," researcher and entomologist

The area covered by the termite complex found in Brazil is the size of Great Britain. (Supplied)

"It's incredible that, in this day and age, you can find an 'unknown' biological wonder, said one expert. (AAP)

Stephen Martin of the UK's University of Salford said in a statement.

"The amount of soil excavated is... equivalent to 4,000 Great Pyramids of Giza, and represents one of the biggest structures built by a single insect species."

The mounds, more of which are still being built, came to scientists' attention when some of the lands were cleared for pasture in recent decades.

The mounds were formed by a single species and are around 4,000 years old, the same as Africa's oldest. (Supplied)

Soil samples collected from the centres of 11 mounds and dated indicated that the mounds were created 690 to 3,820 years ago. That makes them about as old as the world's oldest known termite mounds in Africa, according to a statement posted online by Cell Press.

The mounds are not nests but rather the result of the insects' slow and steady excavation of a network of interconnected underground tunnels, which resulted in waste building up in cones on the surface.

The vast tunnel network apparently allows safe access to a sporadic food supply, similar to naked mole-rats, which also live in arid regions and construct very extensive burrow networks to obtain food, the researchers said.

The soil used to build the complex is the equivalent of around 4,000 Egyptian pyramids. (Supplied)

"It's incredible that, in this day and age, you can find an 'unknown' biological wonder of this sheer size and age still existing, with the occupants still present," Martin said.

The researchers said there are still many unanswered questions about the termite colonies, including the exact physical structure of the nests. No queen chamber for the species has ever been found.

- CNN