Alok, Nigeria - For the past couple of years, these mysterious circles of carved stone figures, which villagers in southern Nigeria still worship on occasion, have been causing a frenzy of excitement.

Newspapers have trumpeted the Ikom monoliths - phallic-shaped pieces of volcanic rock largely ignored for centuries - as being remnants of a glorious civilisation made up in equal parts of Ancient Egypt and the Old Testament.

One theory even cites them as evidence that the biblical Garden of Eden lay in what is now Nigeria.

Nigerian bloggers have been waxing lyrical about a "high technology civilisation based in the present-day location of the Sahara desert". This civilisation, whose "hallmarks included the Sphinx and the Great Pyramid of Egypt", was "decimated by the deluge and by the war of the gods of antiquity".

The stones themselves, which stand between 1 and 1,8 metres high, and which are laid out in some 30 circles in and around Alok village in Cross River State, are intriguing rather than awe-inspiring.

They were recently added to the World Monuments Fund's (WMF) list of sites in danger and are on the "tentative" list for possible inclusion in UNESCO's World Heritage Site list.

If included they would be Nigeria's third site, after Sukhur and the Sacred Forest of Osun.

The most immediate threats to the stones are erosion, exposure to humidity, heavy rainfall and extreme heat and sun, damage from falling trees and theft and vandalism, WMF says.

In the state capital Calabar giant versions of the stones - 20 or 30 times the size of the originals - were constructed last year to decorate a roundabout.

The population knows they come from "somewhere after Ikom", a town several hours' drive to the north.

"The people up there used to worship them; sometimes they still do," ventures a local resident called Wisdom, viewing one of the original stones in the garden of Calabar museum.

But even 20 or 30 kilometres outside Alok, ask for the "big grey stones" and all you will get is a blank look.

Only a cousin of Alok's Chief Sylvanus Ekoh Akong, located by chance at a makeshift roadside bar, was able to show the way.

Chief Sylvanus's monoliths have been given a walled enclosure planted with a huge orange tree, poinsettias and palms. Despite his immense girth, the chief trots from stone to stone, sweat trickling down from under his black felt hat.

He reads into the facial features and geometrical carvings everything from the symbols of leadership to the birth of feminism, fertility, war and peace.

Dates however, are not the chief's strong point - he explains the first archaeologists to study the monoliths in a neighbouring village used carbon dating to put their age at around 2000 years.

More recent studies, he said, also using carbon dating, have estimated the age of the stones at Alok at 4 500 years - that is roughly as old as the Egyptian pyramids.

A question on the likelihood of subsequent civilisations having built the same type of monolith over a period of 2500 years leaves him unfazed.

Ten minutes later he has multiplied the age of the stones by 100 and is assuring his visitors the monoliths are 450 000 years old.

WMF says the stones date from 2000 BC, but it is not clear whether the Fund is using a number supplied by the Nigerian government or whether it has dated the stones independently.

Blood sacrifices anywhere near the stones are forbidden. But on September 14 of each year, the eve of the annual yam harvest festival, the stones are decorated with coloured powder.

Only pre-pubertal children and post-menopausal women, described locally as "women who no longer go sexual" are allowed to do the decorating. The colours are white for peace, blue for fertility and red for bravery.

The decorating ritual is a highly social occasion.

"We laugh amongst ourselves, we joke, we stop for something to drink," explained Eunice Aki who took part this year.

Chief Sylvanus, bursting out of his grey suit, the huge diamante cross round his neck glinting in the sun, held forth on the power of the stones.

"The impure would not dare come in here," he told AFP. "If thieves come in and tamper with one it will crack and will be a bad omen for the community."

As for the thieves: "either they are blinded and cannot find their way out or they are found here legless".

The site first attracted attention from outsiders in the second half of the last century, but it is only very recently that the stones caused excitement in Nigeria itself.

Catherine Acholonu-Olumba, one-time cultural attache to Nigeria's former President Olusegun Obasanjo, is credited with having written a work called "Gram (or Garama - sources differ): Stone writings of African Adam".

This book, co-authored with the "IT specialist" Prince Ajay Prabhakar of India, but seemingly not yet published, either advances the theory or is incorrectly credited with advancing the theory that the Garden of Eden lay in what is now Nigeria, and that, by extension, Adam and Eve were Nigerians.

If the Nigerian press was quick to welcome any theory putting Nigeria in a positive light, the Nigerian government, in its submission to UNESCO, was more circumspect.

In its justification of the stones' "outstanding universal value", the government states that they "bear a form of writing and a complex system of codified information".

"The Ikom monoliths with their geometric inscriptions could be compared to the rock arts of Tanzania. The meanings of the codified symbols are known to only the artists," the submission says, before adding that the stones could be West Africa's answer to Britain's Stonehenge.