Bosnian explorer Semir Osmanagic is convinced he has found Europe's first pyramids which he says are a new world wonder dating back to ancient times.

"I was amazed when I first saw them. I'm deeply convinced now that this is the work of an ancient civilisation built many thousands of years ago," he said while observing an area he excavated north of Sarajevo.

The 45-year-old is so certain two pyramids are hidden in Visoko valley that he has spent some 16,000 euros (20,000 dollars) researching the area, located either side of a river about 30 kilometres (18 miles) from the Bosnian capital. Residents of the nearby town of Visoko have long known about the presence of the two structures they always referred to as 'pyramids' but none of them was ever intrigued enough to investigate further. But Osmanagic, who says he sharpened his eye for archaeology on numerous trips around the world to study ancient civilisations, insists the structures "cannot be the art of nature".

The self-styled explorer with an Indiana Jones-like hat and clothes began his Bosnian pyramid crusade in April this year after visiting the remnants of a medieval royal palace at the top of the hill.

Osmanagic, a businessman and author of several books on other civilizations, says the two "constructions" are precisely aligned with the compass to the four corners of the world.He says he sees astonishing similarities between them and Mexican pyramids dating back to about 200 AD, which also come in pairs, one representing the sun and the other the moon. This is why he calls Visocica hill "The Bosnian pyramid of the sun".

Osmanagic says he believes builders from an unknown civilisation shaped the hill into a 'step pyramid' then coated it with a kind of primitive concrete. The structure now stands some 70 metres (230 feet) high, with a square base that is 220 by 220 metres (730 by 730 feet). After conducting initial probes about 17 metres (56 feet) into the earth that revealed "numerous anomalies in the soil," Osmanagic says he returned to the site with a team of people to start his initial excavation work.

Nadja Nukic, a geologist at the site, said she was most puzzled by three layers of brown polished stone that lie an equal distance from each other underground.

The team began excavating a few spots at the site this week, with the work expected to be completed in two weeks. They hope to be able to uncover one of the pyramid steps and larger pieces the mysterious brown stone for further analysis. To back his insistence that the two structures are ancient pyramids, Osmanagic says his diggers uncovered slabs of polished sandstone that formed the "paved entrance" to the structures. The director of the Visoko Historic Heritage museum, Senad Hodovic, admits he is no sceptic. "The pyramids are obviously the work of man. But we need proper and serious analysis to show who built them and when." Hodovic says he has spent years urging authorities to support archeological research of the plateau of the hill, which is recorded in historic annals as the site of a medieval Bosnian town. He says the shape and monumentality of the pyramids is not typical for Middle Age Bosnian constructions.

Osmanagic, who has lived in the United States for the past 15 years where he runs a metal workshop business, says he has no ambitions of becoming famous. "I'm not doing this for my own glory. I just want to encourage local authorities to seriously deal with this site which could become Bosnia's most profitable product," Osmanagic said.