A nuclear gauge containing a radioactive source is among a number of items stolen from a van in Drogheda, Co Louth.

The van was parked in The Downs, Highlands, and the items were stolen sometime between 6pm yesterday and 6.30am today.

A Troxler Nuclear Moisture Density Gauge containing a radioactive source was taken. The device is used by engineers to measure density and moisture content in construction materials.

The Environmental Protection Agency said there is a potential risk of exposure to radiation, particularly if the case is opened and the equipment is activated.

Gardaí are appealing to any witnesses or anyone who noticed any unusual activity in the Highlands area between 6pm yesterday and 6.30am today to contact Drogheda Garda Station on 041 987 4200, or the Garda Confidential Line at 1800 666 111.

Programme Manager with the EPA's office of Environmental Enforcement Noel Byrne said the gauge is used for engineering purposes to determine the density of compacted material such as tarmacadam roads.

He said it is highly probable that the people who stole the gauge do not realise what they have taken or the potential risk they have created for themselves.

Mr Byrne said the risk of exposure to radiation is based on the length of time and proximity to the source. So, if someone kept their distance greater than 5m and minimised their time near the source, they would see very little effect.

"On the other side, if someone opens the box and attempts to access the radiation source, they could potentially exceed the annual dose limit in approximately 12 minutes."