Seoul, South Korea (CNN) -- North Korea has relieved its army chief of all government posts because of an illness, the state-run news agency said Monday, prompting speculation of a possible power struggle within the secretive regime.
The military official, Ri Yong Ho, was believed to be a close aide to the young North Korean leader, Kim Jong Un, who assumed power in December following the death of his father, Kim Jong Il.
Ri, 69, is considered to have helped Kim Jong Un consolidate power in the ensuing months. The two men and several other top officials led the funeral procession for Kim Jong Il in December.
As well as serving as army chief, Ri held several key government posts, including that of vice chairman of the Central Military Commission of the Workers' Party of Korea, the Korean Central News Agency said Monday.
KCNA said the decision to relieve Ri of all posts was made Sunday at a meeting of senior officials of the ruling Workers' Party of Korea. It did not elaborate on his illness.
One observer of North Korea said the move could represent a struggle between the country's powerful military and its civilian elite.
Andrei Lankov, a professor at Kookmin University in South Korea, said the announcement could show the power of Kim Jong Un's uncle, Jang Song Taek, who was seen as influential in overseeing Kim Jong Un's ascension to power.
"This follows a pattern we have seen since at least last March," Lankov said. "People who can be described as the Jang Song Taek group are taking the upper hand. It seems Jang Song Taek may be removing people who might constitute a threat to him."
Ri's removal may signify the first purge under the leadership of Kim Jong Un, Lankov said. "Not necessarily a bloody one, but the first case of a person of great political significance being removed."
Han Park, a professor of international affairs at the University of Georgia and director of the school's Center for the Study of Global Issues, said observers do not know what may have happened, but may find out soon. "If it is a power struggle of that nature, we will see some ensuing changes in top personnel," he told CNN in a telephone interview. "Unless we see that, it (Ri's stepping down) is really for personal reasons, such as illness."
Park said he saw Ri in April at a banquet in Pyongyang celebrating the 100th anniversary of the birth of the nation's founder, Kim Il Sung. "He didn't appear to be a very healthy person," Park said. "His kind of color is a little dark, and it didn't appear to be very healthy."
Still, he said, he was "shocked" when he heard the news that Ri had been removed from his posts. "He's a very formidable person there," Park said.
Ri was appointed as chief of the army in February 2009, according to a KCNA report at the time.
CNN's Tim Schwarz and Tom Watkins contributed to this report.