Image copyright AFP

US safety regulators have announced a formal recall of the Samsung Galaxy Note 7 after reports of fires caused by faulty batteries.

The South Korean tech giant had already launched a voluntary recall after user complaints about 'exploding' phones.

According to Samsung, the problem affects 2.5 million devices globally, including 1 million in the US.

The recall comes at a crucial time as rival Apple has just released its new iPhone 7 flagship model.

"Because this product presents such a serious fire hazard, I am urging all consumers... to take advantage of this recall right away,'' Elliot Kaye, chairman of the US Consumer Product Safety Commission said.

Mr Kaye said Samsung should not have tried to do the recall by itself, saying: "Anybody who thinks that a company going out on its own is going to provide the best recall for that company, and more importantly for the consumer, needs to have more than their phone checked,"

So far, Samsung has received 92 reports of the batteries overheating in the US, including 26 reports of burns and 55 of property damage, according to the commission's website.

The company said it would speed up its recall, with Tim Baxter, president of Samsung Electronics America saying that "consumer safety is always our highest priority."

What makes lithium batteries catch fire?

Image copyright Ariel Gonzalez Image caption This Galaxy Note 7 reportedly caught fire shortly after its charger was unplugged

Flight warnings

Samsung has come under fire for its response to reports of battery problems over the past weeks.

On 2 September the firm said it would stop selling the phones and offered to replace the ones already sold.

The company last week advised people to stop using the device.

Samsung also said it would limit the batteries of the Note 7 to 60% of their capacity via a software update.

The US Department of Transportation meanwhile has ordered airline passengers not to bring the phones on planes unless they keep them turned off and don't charge them during the flight.

Passengers were even advised against packing the phones into any checked-in luggage.

A number of airlines around the globe have also banned the phone from being used or charged on their planes.

The phone was launched on 19 August and had been generally well-received by critics and consumers.

The Galaxy Note 7 model is the latest of Samsung's series of so-called phablets - smartphones with very large screens.