A New Zealand wildlife park has been forced to euthanise two of their lions, following the closure of the park amid ongoing financial difficulties.

The privately owned Kamo Wildlife Sanctuary, located in the northern city of Whangārei on New Zealand's north island, has been up for sale since August.

The sanctuary said they had been left with no choice when it came to the ageing big cats, which they said had "serious health conditions that were not treatable and were deteriorating".

The fate of the five remaining lions at the property was still unclear, but park operator Janette Vallance said they were exploring "every possibility" in a statement shared on Facebook.

In a Facebook post earlier this week, Ms Vallance said property owners Bolton Equities had initially made the "difficult decision" to euthanise all seven big cats at the sanctuary following their last weekend of trade.