Householders dialled 999 after their porch filled with red smoke from a flare shoved through their letterbox.

Firefighters and police were called to the incident in Chilton Avenue, Sittingbourne.

Crew manager Mat Barney, from Sittingbourne Fire Station, said: “Someone had put a marine-grade smoke flare through.

“They were a couple in their 60s. The lady had heard the letterbox go and assumed it was someone popping a Christmas card through the door."

The couple were advised by the 999 operator to go and wait outside for the emergency services.

Police scenes of crime officers were called in and the flare was taken away for analysis.

CCTV in the area was also due to be looked at.

Mr Barney said the damage was limited to the front door, adding: “This was very dangerous and could have started a fire.

“Hopefully it was someone messing about and it will not be repeated.”

Firefighters also fitted two smoke alarms following the incident on Saturday night. The two fire engines left after about an hour.

A police spokesman urged anyone with information to call 01795 419119 quoting reference XY/050778/16, or Crimestoppers anonymously on 0800 555111.