Kim Jong-Un has been made "Marshal" of North Korea, a title previously held by his late father, Pyongyang said, as the young successor of the communist dynasty tightens his grip on power.
The move came as Hyon Yong-Chol was confirmed as the new army chief after his recent appointment as vice marshal. The promotion was widely expected and sees him replace Ri Yong-Ho who was removed from his post at the weekend.
Analysts said the new title underlined Jong-Un's efforts to reinforce control over the 1.2-million-strong military. The new leader, who is in his late 20s, has made a series of visits to military units since his father died in December.
"A decision was made to award the title of Marshal of the DPRK (North Korea) to Kim Jong-Un, supreme commander of the Korean People's Army," the official Korean Central News Agency (KCNA) said on Wednesday.
The title of Marshal was held by both Jong-Un's father, Kim Jong-Il, and
his grandfather Kim Il-Sung, the North's founding father.
"By donning the mantle worn by the two Kims, Jong-Un is projecting an image as a legitimate successor to the throne and tightening his grip on power," Professor Kim Yong-Hyon of Dongguk University told AFP.
Il-Sung was promoted to "Generalissimo" in 1992, two years before his death of a heart attack, while Jong-Il was posthumously awarded the same title in February.
With Hyon promoted to vice marshal on Monday, Jong-Un, who was made a general in September 2010, apparently needed a new rank befitting the supreme commander of the military, Cheong Seong-Chang of the Sejong Institute said.
"This is the only title left for Jong-Un to decorate himself with after he assumed almost all party and army positions," he said.
Senior military officials and thousands of soldiers gathered in Pyongyang to celebrate Jong-Un's promotion and to pledge loyalty to the new marshal, state TV showed.
KCNA meanwhile said that Hyon was the new army chief, using the official title for the role in a report on the celebrations to mark Jong-Un being named Marshal. It did not say when he officially took on the role.
"Hyon Yong-Chol, chief of the general staff of the KPA (Korean People's Army), offered the highest glory and the warmest congratulations to the respected supreme commander," it said.
Hyon, in his early 60s, was up until recently a low-profile figure. In contrast, 69-year-old Ri had been considered a key regime figure and one of Jong-Un's inner circle, having been seen with him many times in public.
South Korean President Lee Myung-Bak chaired a high-level security meeting Wednesday and ordered officials to closely watch the situation in the nuclear-armed North.
The South's defence ministry said there was no visible change in North Korean military activities along the tense border.
Chinese foreign ministry spokesman Hong Lei described China and the North as "friendly neighbours".
"We wish for the smooth development of North Korea under the leadership of Kim Jong-Un and the Workers' Party of Korea," he said after news of the new title.
Ri was removed from all his posts on Sunday due to "illness", according to state media, a move that took many observers by surprise, with widespread scepticism over the official reason given.
Some analysts said Jong-Un has been purging aged military leaders, including former armed forces minister Kim Yong-Chun, and U Dong-Chuk who ran the secret police.
"The recent changes are all part of his efforts to speed up generational changes in the military and keep the military on a short leash," said Chang Yong-Seok of the Institute for Peace and Unification.
"Granting Jong-Un the title of the country's Marshal will help allay concerns over his grip on power."
Professor Yun Duk-Min of the Korea National Diplomatic Academy said the military's clout had grown out of proportion under the "Songun", or military-first, policy of Jong-Un's father.
It has been actively engaged in farming, fishing and civilian construction projects while controlling most of North Korea's trade, reported to be $6.3 billion last year.