Reports of a red flare off the coast led rescue teams to carry out checks for vessels in distress out at sea.
Sunderland Coastguard Rescue Team and South Shields Volunteer Life Brigade were altered to concerns after the light was spotted in the Marsden area of South Shields.
In a joint statement, the teams said: "On arrival a search of the area was immediately carried out as the light was quickly fading and no vessels were observed in distress.
"After further investigations it was determined the flare was the light from the radio mast off Blyth and the call put to a false alarm with good intent."
The call out happened at 4.40pm today.
Anyone reporting a coastal emergency is advised to dial 999 and ask for the Coastguard.