Gardaí are investigating the theft of 700 litres of diesel from a lorry in Glaslough.
The incident occurred in the Tullyree area of the Monaghan village in the early hours of Tuesday morning.
Security cameras on-board the truck captured a 2007 to 2012 model silver Vauxhall Astra with no number plates pull up alongside it, and it's believed the culprits travelled in this vehicle.
It's understood the diesel was taken after the anti-theft siphoning device on the fuel tank was broken.
No arrests have been made and investigations are ongoing.
Gardaí are interested in speaking to anyone who witnessed suspicious activity in the area, particularly those with dash-cam or CCTV footage.