The Grand Ducal police has issued a warning of a new method used by burglars to test whether a house is empty or not.

Intruders have taken to using thin strings of adhesive on entryways and doors to help them ascertain when a resident has left the property. The strings are usually barely visible, showing if the door has been opened recently.

If the strings are left intact, they function as an indication for burglars that the property is empty, allowing them free rein to break in.

The glue is mostly found around the lower parts of the door, say police. Anyone who notices these glue strings at their home should contact police immediately on the emergency number 113.