SEOUL: K-pop boy band BTS will go off on mandatory military service, starting shortly with oldest member Jin, their agency said on Monday.

Jin, 29, has put off his service for as long as he can and faces the imminent prospect of a full stint - meaning nearly two years out of the public eye - when he turns 30 in December.

Since their 2013 debut, BTS have became a worldwide sensation with their upbeat hits and social campaigns aimed at empowering youth.

"Jin will cancel the request to delay enlistment in late October 2022 and follow the Military Manpower Administration's relevant procedures for enlistment," the seven-member band's management group HYBE said in a regulatory filing.

All other members will also serve the mandatory military duty according to their respective plans, it added.

"Both the company and the members of BTS are looking forward to reconvening as a group again around 2025 following their service commitment," HYBE-owned Bighit Music, which manages BTS, said in a separate statement.

All able-bodied men in South Korea aged between 18 and 28 must serve in the military for between 18 and 21 months as part of efforts to defend against nuclear-armed North Korea. Some categories, however, have won exemptions, or served shorter terms, including Olympics and Asian Games medal winners and classical musicians and dancers who win top prizes at certain competitions. Some lawmakers had called for BTS to be exempted.

BTS announced a break in June from group musical activities to pursue solo projects, raising questions about the band's future.

They reunited to perform a free concert on Saturday in the city of Busan in support of South Korea's bid to host the World Expo 2030 in the port city.