A bag stuffed with what are believed to be Ukrainian melons has Christchurch airport biosecurity staff bewildered.
The mystery bag was recently found unclaimed on the baggage carousel following the arrival of a charter flight from Ukraine.
It contained some 40kg of whole, large melons - one of the biggest fruit seizures of its kind at Christchurch airport, Ministry for Primary Industries team leader south Craig Jorgensen said.
"There have been outbreaks of Mediterranean fruit fly in Ukraine. As melons have the potential to carry this serious pest, they would have been stopped at the border."
The bag, which also contained some shoes, may have been meant to travel domestically only, but ended up on an international flight, Mr Jorgensen said.
"It's also possible that a passenger was afraid to claim the bag, believing they had broken our biosecurity rules."
It was not illegal to travel with fruit and other foods, but that there was a legal requirement to declare or dispose of them before leaving the airport's secure arrivals area.
"This is about protecting New Zealand from pests and diseases that could wreck our economy and natural environment."