Samsung is halting sales of its Galaxy Note 7 smartphones around the world following new reports of fire damage in some devices.

The company has told all affected customers who own an original or a replaced Note 7 phone to power down and stop using their device immediately.

Samsung had formally recalled 2.5 million devices after dozens exploded or caught fire, and was in the process of replacing them.

But there have been multiple reports that the "safe" replacements provided have also overheated, emitted smoke or caught fire.

Authorities in South Korea also say they have discovered a new product defect in the Note 7, but they stopped short of confirming what that safety issue is.

All global partners of Samsung are now being asked to pull the Note 7 from their shelves for the second time in two months while Samsung and regulators investigate the latest claims.

Affected phone users can request a refund or swap their Note 7 for a different Samsung model.

Prior to the announcement, several British phone networks had already suspended the sale of new Galaxy Note 7 handsets - adding that customer safety was of the "utmost importance".

The deepening recall crisis is raising fresh doubts about Samsung's quality control measures, which had long been touted as one of the South Korean manufacturer's unique selling points.

Officials from the US Consumer Product Safety Commission say they are investigating five incidents of fire and overheating at present.

Elliot Kaye, who chairs the commission, said Samsung's decision to halt all sales was "the right move" in light of the ongoing safety issues.

"No one should have to be concerned their phone will endanger them, their family or their property," he added.

Samsung had blamed the spate of fires which sparked the first recall on batteries provided by a particular supplier, and assured customers it was using a different supplier for its replacement phones.

But the latest reports have also brought questions about the real cause of the problem.