Samsung Electronics Co Ltd said today pre-orders for its Galaxy Note 8 premium smartphone have hit the highest-ever for the Note series, beating its predecessor Note 7 over five days by about 2.5 times.

Samsung is banking on the device to protect its market dominance as it competes with Apple Inc's latest iPhones due to be unveiled later today. Note 8 sales begin in the United States, South Korea and elsewhere on Friday.

Pre-orders reached about 650,000 Note 8 handsets over five days from about 40 countries, making the initial response "very encouraging," DJ Koh, president of Samsung Electronics' mobile communications business, said at a media event.

The device succeeds the short-lived Note 7, whose battery fires resulted in Samsung pulling the device from the market after just a couple of months at a cost of billions of dollars.

Its reputation tarnished, the world's biggest smartphone maker by market share nevertheless decided to retain the Note brand after a survey showed 85% of 5,000 Galaxy Note users expressed brand loyalty, Koh said.

The Note 8's US price of $930 to $960, including dialling and data plans, begins an era of premium-priced handsets which analysts expect to be joined by $1,000-plus iPhones.

Apple is widely expected to unveil a special edition iPhone commemorating 10 years of the handset, equipped with edge-to-edge screen and augmented reality, that will compete with the Note 8 for pre-holiday season sales in Western markets.

Koh said Samsung hopes to showcase a foldable handset next year but that technological hurdles must be overcome before a decision can be made.

"We are digging thoroughly into several issues we must overcome, as we don't want to just make a few, sell a few and be done. We want to hear that Samsung made a very good product."