SAQQARA, Egypt (AP) -- Archaeologists have discovered a new pyramid under the sands of Saqqara, an ancient burial site that remains largely unexplored and has yielded a string of unearthed pyramids in recent years, Egypt's antiquities chief announced Tuesday.

The 4,300-year-old monument most likely belonged to the queen mother of the founder of Egypt's 6th Dynasty, several hundred years after the building of the famed Great Pyramids of Giza, the country's antiquities chief Zahi Hawass said as he took the media on a tour of the find.

The discovery is part of the sprawling necropolis and burial site of the rulers of ancient Memphis, the capital of Egypt's Old Kingdom, about 19 kilometers (12 miles) south of Giza.

All that remains of the pyramid is a square-shaped 16-foot (5-meter) tall structure that had been buried under 65 feet (25 meters) of sand.

"There was so much sand dumped here that no one had any idea there was something buried underneath," said Hawass.

Hawass' team has been excavating at the location for two years, but he said it was only two months ago when they determined the structure, with sides about 72 feet (22 meters) long, was the base of a pyramid. They also found parts of the pyramid's white limestone casing -- believed to have once covered the entire structure -- which enabled them to calculate that the complete pyramid was once 45 feet (14 meters) high.

The pyramid is the 118th discovered so far in Egypt. "To find a new pyramid is always exciting," said Hawass. "And this one is magical. It belonged to a queen."

Hawass said he believes the pyramid belongs to Queen Sesheshet, who is thought to have played a significant role in establishing the 6th Dynasty and uniting two branches of the feuding royal family. Her son, Teti, is believed to have ruled for around 20 years until he was possibly assassinated, a sign of the time's turbulence.

Evidence of the identification is still indirect. The pyramids of Teti's two wives, already discovered 100 years ago and in 1994 respectively, lie next to it as part of the burial complex alongside the collapsed pyramid of Teti himself.

The Egyptian team is still digging and is two weeks from entering the burial chamber inside the pyramid, where Hawass hopes they will find proof of its owner -- a sarcophagus or at least an inscription of the queen, he said.

Finding anything more would be next to impossible, as robbers in antiquity looted the pyramid, Hawass added, pointing to a gaping shaft on the structure's top that remains a testament to the thieves' actions.

Dieter Wildung, head of Berlin's Egyptian Museum and a leading Egyptologists in Europe, said Hawass' claim is plausible because it was common in the Old Kingdom for kings to build pyramids for their queens and mothers next to their own.

"Hawass is likely right," Wildung, who is not involved in the dig, said in a phone interview. "These parallel situations give a very strong argument in favor of his interpretation."

Joe Wegner, an associate professor of Egyptian archaeology at University of Pennsylvania who has been involved in other expeditions at Saqqara, cautioned that until "inscriptional confirmation is found, it's still an educated guess" that the pyramid is Sesheshet's.

Although evidence of the queen's existence was found elsewhere in Egypt in inscriptions and a papyrus document -- a medical prescription to strengthen the queen's thinning hair -- the site of her burial was not known.

The find is important because it adds to the understanding of the 6th Dynasty, which lasted from 2,322 B.C. to 2,151 B.C. It was the last dynasty of the Old Kingdom, which spanned the 3rd millennium B.C. and was the first peak of pharaonic civilization.

Saqqara is most famous for the Step Pyramid of King Djoser, built in the 27th century B.C.

Only a third of the Saqqara complex has been explored so far, and recent digging has turned up a number of key finds.

The last new pyramid found there three years ago is thought to belong to the wife of Teti's successor, Pepi I.

In June, Hawass' team unveiled a "rediscovery" at Saqqara -- a pyramid believed to have been built by King Menkauhor, an obscure pharaoh whose pyramid was first discovered in 1842 by German archaeologist Karl Richard Lepsius. But desert sands later covered the pyramid and archaeologists were unable to find Menkauhor's resting place until three months ago.