It is a Christmas message no one wants to hear three days out from the big day: check your Christmas ham.

But authorities are warning families to open the fridge and have a look, with Vic’s Meat 4.5-kilogram hams being recalled for a possible listeria contamination.

The Australian Food Standards body put out the warning on Saturday after a microbial contamination was detected in the product.

The affected hams have a best before date of January 29, 2019 and should be returned for a full refund.

The hams are sold in NSW, Western Australia and Victoria at stores such as Victor Churchill, Simon Johnson and Vic’s Meats.

Vic’s Meat put out a message on Facebook, telling its customers: “Your health and trust is our first and last priority”.

“While remote, we have taken swift and decisive action to recall all potentially affected products and no-one is at risk,” the company said.

“We are currently conducting a detailed investigation to determine how our meticulous processes, which span two decades may have been compromised.

“All other hams and products are unrelated and present no risk.”

The listeria bacteria is known to cause serious health issues for pregnant women, the elderly and people with weakened immune systems.

The incubation period – between infection and symptoms – can vary from three to 70 days but on average is about three weeks.

According to NSW Health, the illness causes death in about one third of all patients.

-ABC