Samsung Electronics defied speculation it would drop the head of its underperforming mobile division, as the Samsung Group's heir apparent opted to keep the man his ailing father appointed while the patriarch's future is uncertain.

Staff at Samsung have been waiting nervously for the annual reshuffle after a weak smartphone performance and the worst earnings in three years, with many fearing for their jobs, but embattled co-chief executive JK Shin now knows he will continue to head the Electronics unit's mobile division despite sagging smartphone sales.

Semiconductor business chief Kwon Oh-hyun and consumer electronics head Yoon Boo-keun also kept their jobs.

Analysts said Jay Y Lee, likely successor and only son of group patriarch Lee Kun-hee, opted to keep his father's key lieutenants in place to ensure stability and consolidate his own position.

Samsung Group Senior Vice President Lee June reminded reporters that Mr Shin was "a major contributor in Samsung Electronics' emergence as the top global player in the handsets business" and would be given an opportunity to turn the business around.

Squeezed by Chinese rivals like Xiaomi Technology Co Ltd at the low end and Apple Inc's iPhones at the top, Samsung Electronics' share of the smartphone market has shrunk year-on-year for the last three quarters, leading to speculation Shin's days were numbered.

Samsung Electronics insiders said employees' focus was now on any follow-up management appointments and reorganisation plans due for the firm later this week.