A Palestinian Gaza resident has accidently found on Friday ancient burial complex consisting of nine graves in a garden after flash-flooding uncovered access to a hidden staircase.

AbdelKarim Kafarna,24, a resident of Beit Hanoun district, said he found the graves while trying to found where water was running into the earth after heavy rains earlier this week.

"I discovered the place where the water was falling in," he told AFP news agency, saying he had lifted a stone and found steps leading down into the ancient tomb, some four meters under the ground.

He said some of the graves had bones, along with votive lamps and other ceramic.

Local archaeologists argue that the site dates back 2,000 years to the time when the area was part of the Roman Empire.

"The burial and excavation methods in this tomb date it back to the Roman period, but it may have continued in use into the early Byzantine period," Gaza-based archaeologist Ayman Hassouna said.