K-pop megastars BTS will release a memoir in South Korea and the United States in July, its US publisher said, triggering feverish excitement from the supergroup's global fanbase.

BTS has become a global cultural phenomenon, selling out stadiums and dominating charts around the world while raking in billions for South Korea's economy.

Titled "Beyond the Story: 10-Year Record of BTS", the book was co-written by South Korean journalist Kang Myeong-seok and members of the band, according to the publisher.

"Who is excited?... #BTSbook," US publisher Flatiron Books said Thursday on its Instagram account, sharing a news article about the launch.

Online forums and social media sites had been awash with speculation about a potential celebrity book release in July, with some commenters saying that it may be authored by Taylor Swift.

The mystery book shot to the top of Amazon and Barnes and Noble bestseller lists after pre-orders by fans.

The K-pop group's 544-page memoir will be released on July 9, according to the book's Amazon page.

It is a tribute to a significant date in the septet's history: the megastars' loyal international fan base known as ARMY came into being that day, 10 years ago.

"I'm so looking forward to the book... It's so cool to be able to look back on the last 10 years with BTS," one fan wrote on Twitter in Korean.

"Will I be able to buy it since the competition is so global?" another feared.

The US edition of the book was translated by Anton Hur with Clare Richards and Slin Jung, Hur said in a tweet.

BTS are currently on a "hiatus", with members pursuing solo projects while two of the group have enlisted for mandatory South Korean military service.

All able-bodied men in South Korea must serve at least 18 months in the military and, after a years-long debate about whether BTS deserved an exemption, Jin, the oldest member of the group, enlisted last year.

BTS star J-Hope started his mandatory South Korean military service last month, South Korean media reported at the time, becoming the K-pop juggernaut's second member to enlist.

Before the pause, BTS bagged six No. 1 hits on the Hot 100 and all seven members of the boyband have reached the top songs chart with solo tracks, Billboard said.