MEXICO CITY (REUTERS).- Archeologists have uncovered more than 500-year-old remains of about 50 Aztec children, some of them stuffed into ceramic jars for burial, during excavations for a new subway line in Mexico City.

The team from Mexico's National Institute for Anthropology and History also found the foundations of Aztec homes, hundreds of small figurines, and pots and plates dating from 1100 to 1500 AD, on the eve of the Spanish conquest, along the 15-mile (24-km) subway line, due to open in 2012 in southern Mexico City, home to about 20 million people.

"In total there are 60 graves, 10 adults and around 50 children of different ages, some two or three years old," archeologist Maria de Jesus Sanchez told Reuters.

The graves, found scattered in excavation areas since builders began digging the subway line in September 2008, reflect burial practices of the Aztecs, who often interred their dead relatives underneath their homes.

The Aztec empire, with its capital in modern-day Mexico City, held sway over a large part of Mesoamerica for about a century until the arrival of the Spanish.

Deceased children were often placed in earthen vessels before burial in the belief that the jars would resemble the mother's womb and keep them warm.

Among the objects found was a 20-inch (50-cm) stone figure of a woman discovered under the graves of two children, close to the site of a new subway stations.

The subway line links several suburbs that were built on the site of centuries-old Aztec towns. In one suburb, Culhuacan, archeologists found fragments of pots and stone carvings of faces dating back as far as 2000 BC.

Mexico has around 40,000 registered archeological sites.

While officials today have the authority to halt or alter construction work if an important artifact is discovered, many historical sites have been destroyed during construction and infrastructure projects in the past.

(Reporting by Miguel Angel Gutierrez; writing by Sarah Grainger; editing by Missy Ryan and Cynthia Osterman)