Sales of big-screen smartphones will soar in coming years as people who game or watch videos on the go opt for "phablets" with near tablet-size views.

Phablets, a moniker created by combining the words "phone" and "tablet," will prove particularly popular among mobile gamers in South Korea and in China, where people will be drawn to high-quality viewing of online content, according to Britain-based Juniper Research.

Juniper forecast on Tuesday that shipments of phablets, typically described as smartphones with screens of 5.6 inches (142 millimeters) or more when measured diagonally, will breach 120 million units by the year 2018.

An estimated 20 million phablets were shipped last year, according to Juniper.

The phablet market will be dominated by devices powered either by Microsoft's Windows or Google's Android operating systems unless Apple weighs in with a big-screen iPhone, Juniper predicted.

"This dynamic could change dramatically if the rumors of an Apple phablet, which meets Juniper's definition of a 5.6-inch display, were to be realized," the research firm said in its report.

Apple is fighting for share in China's competitive smartphone market, with chief executive Tim Cook personally taking part in the launch Friday of iPhone on the country's biggest wireless provider, China Mobile.