Officers were sent to investigate after a member of the public reported seeing children digging holes in the sand near Newburgh Golf Club. They searched the area and found a hidden entrance which led to a network of tunnels.
A spokesman for Police Scotland said: "These tunnels were dug deep into the sand dunes, shored up with pieces of wood and found to be in an extremely dangerous and unstable condition. Staff from the Newburgh Golf Club using diggers assisted in making the area safe by excavating the tunnels and filling in the area concerned."
The names of youngsters seen carrying spades and other equipment near to the sand dunes have been passed to police and Constable Ian Ivancic will be visiting the youngsters at their homes to speak to them and their parents.
The spokesman added: "Constable Ivancic pointed out that the dunes are a naturally unstable environment and tunnelling would put lives at risk."