The lead singer of one of Korea's most popular boybands has died aged 27.

Kim Jong-hyun - known as Jonghyun - performed as part of the chart-topping act SHINee. He is believed to have taken his own life, according to Reuters via local reports.

Police reportedly found the singer unconscious in his apartment in Cheongdam-dong in the Gangnam district after his sister filed a report with concern for his welfare.

"On 18 December, 2017 at 4.42pm, Jong-hyun's older sister reported to police that her brother was about to take his own life," a statement said.

Tributes from heartbroken fans have poured in on social media. One tweeted: "Such a strong vocalist and such a good songwriter."

Another said: "He wrote one of my favourite K Pop songs, 'Breathe'. He had so much more to give. I'm so sorry he was in so much pain to do this. RIP Kim Jong Hyun."

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SHINee, originally formed in 2008, released their fifth Japanese album Five this year and toured in Japan until April. Referred to as "the Princes of K Pop" thanks to their incredible dance routines and live performances, they achieved hits with songs including "Replay", "Dream Girl" and "Sherlock".