Samsung Electronics on Tuesday unveiled a foldable smartphone and put 5G mobile network capabilities into all of its other flagship devices as it strives to retain the mantle of biggest global phone company.

Samsung's second attempt at a folding phone comes as the South Korean firm fends off its rivals, Apple and Huawei that have eaten into its sales in China and Europe.

The Galaxy Z Flip, with folding glass, starts as a large square when closed and expands to look like most smartphones.