It is the latest find to be made in a sleepy oasis which shot to international prominence last year when Egyptian officials announced the discovery of a vast burial ground full of mummies.
Now archaeologists believe they have found the body of the powerful local governor, Gad Khensu Eyuf Ankh, who ruled the oasis of Bahariya in the Western Desert during the rule of the Pharaoh Apris in the 7th Century BC.
The official in charge of excavations in Bahariya, Zahi Hawass, said archaeologists had been searching for the tomb for decades and had stumbled on it by chance.
Hieroglyphs on the colourfully painted walls proved the crew had found the celebrated mayor's tomb.
It is the latest find to be made in a sleepy oasis which shot to international prominence last year when Egyptian officials announced the discovery of a vast burial ground full of mummies.
Archaeologists are continuing to work in what has become known as the Valley of the Golden Mummies, where they believe as many as 10,000 bodies from the Graeco-Roman period may be buried.
More than 200, some wearing gilded masks, have so far been uncovered.
The mayor's mummified body, mostly decayed, lay inside two finely carved sarcophagi - one inside the other.
Paintings on the holy walls of the temple portrayed the mayor on a level with the pharaoh.
"Everyone was looking for the mayor because he was a very important man," said archaeologist Zahi Hawass.
"It is the most fascinating discovery I have ever made."
The tombs had not been accessible before, becauset houses had been built on top of them. People have only recently moved out of the area.
Most of the dead were from poor or middle class families..
X-rays - performed for the first time at an Egyptian archaeological site - suggest that most of those buried were between 30 and 40 when they died. Kidney and liver diseases were the most likely cause of death because of the high level of iron in local water.
"Every day we understand more about the people who lived here," said Zahi Hawass.
"This is the most scientific excavation ever done in Egypt."
He said the tombs would not be open to the public, and his team was covering up the latest findings as the season ended.
"A lot of our work is about preservation and conservation of the mummies and artefacts," he said.
"We leave most as we found them and exhibit some in the Bahariya Museum."