Fire and Emergency New Zealand were called to the latest incident at 7.30am today where multiple fires were lit in a pathway of trees.
Crews from Oamaru and Waitaki Rural Fire Brigades attended.
Single fires had also been lit yesterday and on Wednesday, August 11, at the reserve.
Waitaki deputy principal rural fire officer Mike Harrison said the fires were being treated as suspicious.
They were ‘‘not acceptable’’ and putting homes and firefighters at risk, he said.
Waitaki Rural Fire Brigade deputy controller Blair Brosnan echoed Mr Harrison, saying the blazes were a ''real concern''.
‘‘Not only could it potentially become a very big fire, the risk to life and property is very big here with it (the reserve) being surrounded by urban property,’’ Mr Brosnan said.
Senior Sergeant Jason McCoy, of Oamaru, confirmed police were investigating the fires.
