SoftBank Group Corp. is considering selling its stake in the Finnish gaming company Supercell Oy, according to people familiar with the matter.

Supercell, which makes games for mobile phones including "Clash of Clans" and "Boom Beach," has held talks with potential strategic buyers based in China, the people said. The process is at an early stage and SoftBank may choose not to sell the stake, they said.

A sale could value the whole of Supercell at more than $5 billion, one of the people said.

SoftBank acquired a majority stake in the Helsinki-based developer for about $1.5 billion in 2013. It increased its stake to 73 percent in May last year. The rest of the company is owned by Supercell's management and employees.

Supercell has struggled to translate the global popularity of "Clash of Clans" into subscriber numbers in Japan, a market that rivals the U.S. in size. Buddy Marini, the head of Supercell's Japan operations, has called the country "the toughest market in the world."

Asian companies have been investing in game developers in recent years, seeking exposure to the fastest-growing part of the gaming industry.

Tencent Holdings Ltd. in 2014 invested $126 million in Glu Mobile Inc., a San Francisco-based company that has produced smartphone games featuring Kim Kardashian and Katy Perry. Mobile developer Kabam Inc., also based in San Francisco, received a $120 million investment from Alibaba Group Holding Ltd. in 2014 as part of a plan to distribute titles like "Lord of the Rings" in China.