Footage showing interior of a 1,500-year-old Mayan tomb Reuters

A small, remote-controlled camera lowered into an early Mayan tomb in southern Mexico has revealed a funeral chamber apparently intact, with offerings and red-painted wall murals, researchers say.

Footage of the approximately 1,500-year-old tomb, at the Palenque archaeological site, shows a series of nine figures depicted in black on a vivid, blood-red background. Archaeologists say the images from one of the earliest ruler's tombs found at Palenque will shed new light on the early years of the once-great city state.

The national institute of anthropology and history said archaeologists had known about the tomb since 1999, but were unable to enter it because the pyramid standing above it was unstable and breaking into the chamber could damage the murals.

It said the floor appeared to be covered with detritus and it was not immediately evident in the footage if the tomb contained recognisable remains. But archaeologist Martha Cuevas said the jade and shell fragments seen on the video were "part of a funerary costume".

Exterior of the tomb in the ancient city of Palenque. Photograph: Reuters

The chamber was found in a heavily deteriorated pyramid complex known as the Southern Acropolis, in a jungle-covered area of Palenque not far from the Temple of Inscriptions, where the tomb of a later ruler, Pakal, was found in the 1950s.

While Pakal's tomb featured a famous and heavily carved sarcophagus, no such structure is seen in the footage of the tomb released on Thursday. The institute said it was "very probable that the fragmented bones are lying directly on the stones of the floor".

But Cuevas said the discovery shed new light on early rulers, and its proximity to other burial sites suggested the tomb may be part of a funerary complex.

"All this leads us to consider that the Southern Acropolis was used as a royal necropolis during that period," Cuevas said.

Susan Gillespie, an associate professor of anthropology at the University of Florida who was not involved in the project, said: "This is an important find for Palenque and for understanding early classic Maya history and politics." She said the later rulers who made the city-state larger tended to build on top of their predecessors' temples and tombs, making it hard to get at them.

"Palenque was a relatively important western Maya capital in the early classic, but with the buildup during the time of Pakal and some of his successors, those accomplishments were buried and thus difficult to assess, buried literally by late classic structures atop early classic ones," Gillespie wrote.

The later rulers wrote almost obsessively about Palenque's history in long stone inscriptions, but Gillespie noted that "finding archaeological confirmation of the earlier kings has been extremely difficult".

The tomb's floor occupies about 5 sq metres, with a low, Mayan-arch roof of overlapping stones. Experts say it probably dates to between 431 and 550 AD, and could contain the remains of K'uk' Bahlam I, the first ruler of the city state.

The tomb's existence was revealed by a shaft found near the top of the ruined pyramid, leading downward. But at 15cm wide, the shaft was too narrow to provide any kind of view of the chamber. In late April, researchers lowered the tiny 5cm-long camera into the tomb.

While the general public had not seen images of the interior of the tomb, video of it was made after the chamber was detected in 1999, said David Stuart, a specialist in Mayan epigraphy at the University of Texas at Austin.

The images had circulated among researchers and been posted on the internet, and Stuart said that some evidence suggests the tomb "is the burial of a noted female ruler of Palenque named Ix Yohl Ik'nal, based on the date and on the identities of ancestral figures painted on the walls".

"The female ruler is mentioned in a number of the historical texts of the site," Stuart wrote.

It would not be the first tomb of a female noble found at Palenque. In 1994, archaeologists found the tomb of a woman dubbed the Red Queen because of the red pigment covering her tomb. But it has never been established that she was a ruler of Palenque, and her tomb dates from a later period, between 600 and 700 AD.