A RUNNER has uncovered piles of homemade spikes on a dirt track in New South Wales.

The man found the devices shortly before midday on Monday while running along Alexanders Trail in Lake Macquarie State Conservation Park at Bolton Point.

Police were told he had been running along the bushland trail when he noticed a pile of leaves in the middle of the track.

"Hidden in the leaves the man found wine corks with nails protruding from them, similar to historic weapons known as caltrops," police said in a statement today.

"The man continued along the trail and found a further two piles hiding more spikes."

Caltrops are devices with a number of metal points ensuring they always project upwards.

The centuries-old weapon was historically thrown on the ground to hinder the enemy by hitting horse hooves or puncturing tyres.

Local officers were notified at 12.40pm and have since released images of the items found.

Police are urging anyone who may have information or who noticed suspicious activity in the area to contact Toronto Police Station on (02) 4088 1099 or Crime Stoppers on 1800 333 000.

A caltrop, made up of two or more sharp nails or spines, is considered a prohibited "miscellaneous article" in NSW under the Weapons Prohibition Act 1998.