A school sports day in Japan has been cancelled after more than 100 deadly Australian black widow spiders were found in a ditch on the playing field.

The nest of the highly venomous spiders was discovered on 20th October, just a day before the event was set to start in the city of Oita, on Kyushu Island.

A teacher at the Misa Elementary School raised the alarm after they found one of the spiders on the school grounds.

Redback spiders (Latrodectus hasselti), also known as Australian black widows, belong to the Theridiidae family and are a close relative of the notorious Black Widow spider (Latrodectus mactans), with one of the main differences being that one has a red dorsal stripe.

Frantic searches then found 100 more of the distinctive creepy crawlies along with unhatched egg sacs.

Although they were exterminated using insecticide, more spiders and egg sacs were found the following day.

The Redback spiders’ bite can kill humans in some rare cases and causes intense pain, muscle weakness, nausea, and vomiting plus sweating, and an increased heart rate.

Experts say that in some cases babies have died within hours of a bite but adults can take up to 30 days to die.