By Hyunjoo Jin

SEOUL (Reuters) - South Korean prosecutors requested on Monday a five-year jail term for Samsung Electronics Chairman Jay Y. Lee over actions in a controversial merger of affiliates that helped solidify his control in a case being tried at an appeals court.

Lee was found not guilty in February of accounting fraud and stock manipulation by a Seoul Central District Court but the prosecutors appealed the ruling.

The appeal hearings, which wrap up on Monday, come at a time when Lee faces growing questions about his ability to lead Samsung, the world's top memory chip and smartphone maker, as it grapples with slowing profits and falling stock prices.

Lee and other former executives had been accused of engineering a merger between two Samsung affiliates - Samsung C&T and Cheil Industries - in a way that dealt poorly with the interests of minority shareholders.

In the closing arguments, state prosecutors said Lee acted in the merger to benefit his personal standing as the de-facto leader of the Samsung conglomerate at the expense of shareholders and investors.

Lee, a third-generation leader of the Samsung Group, has been dogged over the past decade by lawsuits, jail time and attacks from foreign hedge fund Elliott over the 2015 merger of the affiliates that helped tighten his grip on the sprawling conglomerate, after his father was hospitalised due to heart attack in 2014.

(Reporting by Hyunjoo Jin, Hyunsu Yim and Jack Kim; Editing by Ed Davies)