Immigration New Zealand has issued a warning to anyone who might try to reach New Zealand illegally by boat - "There is every chance you will drown at sea."

The department said it would not comment on specific reports that a boat carrying more than 100 illegal migrants might be attempting to travel to New Zealand but said such a mass arrival was a possibility New Zealand should be prepared for.

Police in Southern India are investigating the suspected attempt to illegally transport more than 100 Indian people, including women and children, by boat to New Zealand, media agencies have reported.

A Kerala State police spokesman told the Associated Press police were questioning people who were to have boarded the fishing boat which reportedly left from Munambam Harbour near Kochi in Kerala on January 12.

Police began investigating when they found dozens of abandoned bags containing "everything needed for a sea journey" at the harbour, said spokesman MJ Sojan.

"The boat is gone, that's for sure," he told the AP.

The boat was carrying people from Delhi and Tamil Nadu, two officers involved in the case told Reuters.

A person from New Delhi arrested in connection with the investigation told police the boat was heading to New Zealand, they said.

It is not clear where the overcrowded fishing boat is now.

Immigration New Zealand (INZ) assistant general manager Stephen Vaughan said INZ did not comment on specific ventures but it was aware that people-smugglers continued to express interest in targeting New Zealand.

"We remain vigilant to any possible venture. While reports of these types of ventures are concerning, the message to anyone contemplating such a journey is simple: Any attempt to reach New Zealand will put your life, and the lives of your family members, at great risk. There is every chance you will drown at sea." 

Although there had never been such a mass arrival in New Zealand, there was no doubt it was a target for people smugglers and it was a possibility that the country needed to be prepared for, he said.

The office of Immigration Minister Iain Lees-Galloway could not be reached for comment this morning.

Prime Minister Jacinda Ardern was unable to comment this morning.

Speaking to reporters from London where she has been pushing New Zealand's case on trade, Ardern said she had not been briefed on the report.