SEOUL (AFP) - North Korean state media confirmed on Thursday that the nation's hawkish, ageing army chief has been replaced in a reshuffle that observers say sought to tighten leader Kim Jong-Un's grip over the military.

Rumours had circulated in August that Kim Kyok-Sik, 75, had been replaced as chief of the army's general staff by Ri Yong-Gil.

Ri, believed to be in his 60s, had been previously mentioned as a three-star general and head of the army's general staff operations department but made public appearances in late August with the insignia of a four-star general.

A state media report identified Ri as chief of the general staff of the Korean People's Army, while listing top army officers who accompanied Kim Jong-Un on a visit to the Kumsusan Palace of the Sun at midnight on Wednesday.

The palace is a mausoleum in Pyongyang where the embalmed bodies of former leaders Kim Il-Sung and Kim Jong-Il lie in state.

In a report in August on top-ranking officials attending a football match in Pyongyang, the official Rodong Sinmun daily named Ri ahead of Jang Jong-Nam, the defence minister, while Kim Kyok-Sik was not mentioned at all.

The report sparked speculation that Kim may have been sacked barely three months after he was named army chief.

Kim was seen as a hardliner who reportedly ordered the shelling of Yeonpyeong island in November 2010 when he commanded the North's Fourth Army Corps.

The North's young leader has substantially reshuffled his military top brass since taking over the reins of power from his late father Kim Jong-Il in December 2011, in an apparent attempt to secure his leadership.