SEOUL - A top K-pop star wrote in a suicide note that he was "broken from inside" and "engulfed" by depression, it emerged Tuesday as his death sent shockwaves among fans worldwide.

Kim Jong-Hyun, 27-year-old lead singer of the hugely popular K-pop boyband SHINee, was found in a hotel room in the South Korean capital Seoul in what police said was suicide.

A coal briquette was burning on a frying pan - a common method of self-killing in South Korea, an ultra-competitive society with one of the world's highest suicide rates.

Kim's close friend, musician Nain9, released a suicide note on her Instagram account, saying he had asked her to publish the message in the event of his death.

"I am broken from inside. The depression that gnawed on me slowly has finally engulfed me entirely," it said, adding he "couldn't defeat it anymore".

"I was so alone," he went on. "The act of ending is difficult. I've lived until now because of that difficulty."

"Please tell me I did a good job," he implored, ending the note with: "You've worked hard. You've really gone through a lot. Goodbye."

The five-member SHINee debuted in 2008 and went on to lead the "Korean Wave" that saw South Korean pop culture develop a fan base across Asia and beyond.

Known for peppy songs and carefully-choreographed dance numbers performed with military precision, SHINee have become one of the world's best-known K-pop acts.

Hundreds of Kim's tearful fans paid their respects at a mourning altar in the Seoul hospital where his body lay.

"I came here to say the last farewell... since we fans apparently couldn't be there for him when he needed help most," said Jung Min-Kyung, 19.

Social media was flooded by thousands of messages of mourning, and in the hours after his death it was the top trending topic on China's Twitter-like Weibo, with more than 140 million views. - AFP