Rescue helicopters from Dunedin and North Otago, along with search vessels from Oamaru and Moeraki, were dispatched about 3pm, after about five sightings of flares led to fears an aeroplane or boat may have been in strife.
A report is also thought to have been made to police that a plane had crashed into the sea.
However, Sergeant Craig Sew Hoy said the search was stood down about 4.30pm, after a search around Oamaru Harbour and Cape Wanbrow failed to find any sign of anyone in distress.
A ''substantial'' grid search had been conducted around the Oamaru coast by two boats and two helicopters, including the Dunedin-based Otago Regional Rescue Helicopter, he said.
''Witnesses believe that these flares may have been set off in the Oamaru Creek-Oamaru Harbour area, possibly land-based, or very close to land, according to the witnesses.
''Nothing was located off the coast and police are continuing inquiries to see if there is any other explanation for it.''
Although one witness had yet to be spoken to, police were not yet treating the incident as a hoax, and all avenues of inquiry were still open, he said.
Police would like to hear from anyone who might have set off flares in that area, or who might be missing flares, he said.
No local aircraft or boats had been reported overdue or missing, he said. andrew.ashton@odt.co.nz
