Largs Lifeboat volunteers responded to a report of a 'Red Flare' in an area close to Toward Point.
The emergency call-out happened on Friday 8 November at 5.15pm.
Alasdair Woods, spokesman for the RNLI said: "As the Largs crew searched the area shore based coastguard rescue teams searched the shoreline, two other vessels responding to a broadcast by the UK Coastguard who also joined in the search.
"After an extensive search nothing was found and all units were stood down pending further investigation."
The lifeboat returned to station at 7.30pm. to be made ready for her next service.
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