Photo: Concrete Playground

Investigators have been told the Dynon Road path, particularly on the bend between Dynon Road and Arden Road, has been subject to oil spills over the past three weeks.

The Capital City Trail has also been affected.

The incidents are believed to be deliberate acts, with the latest occurring overnight.

The dangerous spills have caused cyclists to lose traction and control of their bikes.

Police have been told one rider required medical attention after falling as a result of the oil and have called on the injured cyclist to contact Constable McCormack at Melbourne North Police Station on 8379 0800.

All cyclists are urged to take care while riding.

Anyone with information or who may have witnessed any suspicious activity in the area is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report at www.crimestoppersvic.gov.au.