An open and exposed white powdery substance was discovered deposited in a letter slot at the St. George's Post Office.

On Monday staff at the Post Office discovered the substance on the mail which they were retrieving from the overnight receptacle where customers can deposit their mail without entering the Post Office.

Police, Fire and Health Departments were called and removed the substance for testing, and a full investigation is now underway.

The Postmaster General issued a statement in which he said: “We have not been informed as to the results of any tests which have been performed on the mail taken away.

“The St. George's Post Office is to be closed until the substance is identified and declared harmless.”