New Zealand phone shops have stopped offering replacement Samsung Galaxy Note 7s as the Korean tech giant warns customers to turn off their devices and take them back over safety fears.

Samsung on Tuesday (NZT) announced it was stopping all sales and exchanges of the phone globally while reports of overheating and fires in replacement models are investigated.

In a statement, Samsung said anyone with either version of the Note 7 "should power down and stop using the device and take advantage of the remedies available".

Vodafone, Spark and 2degrees hours earlier put a halt to swapping out customer's Note 7s for new ones over safety concerns.

Samsung recalled 2.5 million Note 7s just weeks after launch in September, following dozens of reports of battery fires.

But in the last week, reports of the replacement models overheating - including one smoking on a Southwest Airline flight - have emerged, prompting what the company called a "temporarily adjusting" of production.

Although no cases have been reported in New Zealand, Spark on Monday night said it was "pausing" replacement.

It is offering customers credit refunds for either version of the phone.

Vodafone likewise said it was no longer offering replacements and says customers with either the old or replacement models can refund or exchange them.

2degrees have asked customers to bring them in to the store they got them for an exchange or refund.

An investigation by Samsung found faulty rechargeable lithium batteries from one of its suppliers were the cause of the original fires and the new reports are currently being investigated.

"We remain committed to working diligently with appropriate regulatory authorities to take all necessary steps to resolve the situation," Samsung said.

The issue prompted airlines from around the world to begin either banning use or charging of the phone on flights.