Samsung launched Wednesday the newest version of its oversized smartphone Galaxy Note, just a week after Apple's iPhone 5 hit shelves, in an apparent bid to outpace its rival with a wider range of gadgets.

The South Korean electronics giant said the Galaxy Note II -- first unveiled at a trade fair in Berlin last month -- will eventually hit stores in 128 nations including the United States, where the firm's recently lost a $1.05 billion patent case to Apple.

The gadget is slightly bigger than the firm's flagship smartphone Galaxy S series and comes with a stylus "S pen" to write notes or draw on the screen.

"We believe global sales of Galaxy Note II for the first three months will be more than three times those of the previous version," J.K. Shin, the head of Samsung Electronics' mobile unit, told reporters.

The world's top smartphone maker has sold more than 10 million units of the first Galaxy Note since its debut in November and more than 20 million of the latest Galaxy S III, which was launched in late May.

"It took us some time to establish this new product category in the global market... but now we get far better response than the past," Shin said.

The launch comes after a flurry of new devices from major phone makers including Apple, whose iPhone 5 just days ago enjoyed a record launch weekend with sales topping five million.

Samsung's smaller rival LG Electronics last week put on sale the new version of its headline Optimus G, hopes it will help the world's number five phonemaker meet its goal to sell 80 million mobile phones this year.

Galaxy Note II -- powered by Google's Android software -- is equipped with a new 1.6 GHz quad-core processor that helps run multiple applications faster than the dual-core processor of the previous version.

About 15.1 centimetres long (5.9 inches), 8 centimetres wide, 9.4 millimetres thin and featuring a 5.5-inch touchscreen, it allows users to split the screen in half to view two programmes at once.

"You can exchange chat messages or take part in a video conference while checking e-mails, or take notes while watching a video speech by famous speakers," said Shin.

Samsung has been embroiled in a long-running patent battle with Apple in 10 countries, including the United States and Germany, with the two rivals accusing each other of stealing design and technology.

Last month the South Korean firm was ordered to pay Apple $1.05 billion in damages for illegally copying iPhone and iPad features for its Galaxy S smartphones.