Samsung says global sales of its Galaxy Note 7 are to be halted while it probes reports of replacement handsets catching fire.
The technology giant said owners of either an original Note 7 or a replacement should turn them off and stop using the gadgets.
It comes after multiple claims from the US said replacement devices are still suffering from what Samsung had identified as a "battery cell issue" caused by a "rare manufacturing defect".
Samsung said it is "working with relevant regulatory bodies to investigate the recently reported cases involving the Galaxy Note 7".
"Because consumers' safety remains our top priority, Samsung will ask all carrier and retail partners globally to stop sales and exchanges of the Galaxy Note 7 while the investigation is taking place," the firm added in a statement.
The UK release date for the Note 7 had been moved to October 28, after Samsung ordered a recall of its latest handset following dozens of reports of devices overheating worldwide.
The Korean manufacturer then began a programme offering replacement phones to consumers who had pre-ordered the device in the UK.
Samsung said in September that it was "confident" it had completely overcome the problem and was ready to launch the device.
However, concerns were raised over further defects beyond the battery cell, following several reports in the US of phones catching fire that showed the green battery icon Samsung added to replacement phones to mark them as safe.