Samsung on Wednesday unveiled its first folding handset as part of an effort to rev up demand in the slumping smartphone sector.

The South Korean giant's Galaxy Fold, unveiled at a San Francisco event, services as a smartphone with a 4.6-inch display and unfolds to become a tablet of 7.3 inches.

“We are giving you a device that doesn't just define a new category, it defies category,” said Samsung's Justin Denison at the event.

The new device will be available April 26 starting at $1,980, the company said.

The move comes with the smartphone market in its worst-ever decline with consumers keeping devices longer and waiting for new innovations.

Samsung made the announcement on the home turf of rival Apple, with the two giants battling for the premium segment of the market.

Denison said the Fold is “a one of a kind luxury device with immersive visuals,” and offers “a truly next generation experience” that enables multitasking on its large screen.