Content Warning: This article discusses sensitive topics including death and substance abuse. Reader discretion is advised.

The sister of One Direction member Liam Payne shared a heartfelt message to him on Saturday, in the latest poignant tribute from around the world following his death earlier this week.

In a statement directly addressed to her late brother, who died Wednesday in Argentina, Ruth Gibbins said she does not "feel this world was good enough or kind enough to you".

"My brain is struggling to catch up with what's happening and I don't understand where you've gone," she posted on Instagram.

"Quite often over the last few years, you've had to really try hard to overcome all that was being aimed at you.

"You just wanted to be loved and to make people happy with your music," she added.

On Friday, Payne's father visited the Buenos Aires hotel where his son plunged to his death from a third-floor balcony two days earlier, thanking fans gathered nearby in a shared moment of grief.

After landing in the Argentine capital that morning, Geoff Payne also visited the morgue where the body of his 31-year-old son was being kept pending the results of toxicological tests.

Meanwhile reactions continued to stream in, including from Girls Aloud star Cheryl Tweedy, Payne's former partner and the mother of their seven-year-old boy, Bear.

She called his death an "earth shattering event".

In a social media message, Tweedy hit out at "abhorrent reports and media exploitation" following Payne's passing, which were causing "further harm to everyone left behind picking up the pieces". 

"Before you leave comments or make videos, ask yourself if you would like your own child or family to read them," she said.

"Please give Liam the little dignity he has left in the wake of his death to rest in some peace at last."

Payne died from "multiple traumas" and "internal and external hemorrhaging" after falling from the balcony of his room at the Casa Sur hotel in central Buenos Aires, an autopsy found.

Investigators said he appeared to have been "going through an episode of substance abuse."

Among others to pay tribute on Friday was Simon Cowell, the creator of and judge on "The X Factor" show that launched One Direction in 2010.

Cowell said he was "truly devastated", in an Instagram post also spoke directly to Payne.

"I want you to know how much love and respect I have for you," he said.

"I watched you spending so much time with people who had wanted to meet you. You really cared."

Cowell added that a meeting with Payne last year reminded him "that you were still the sweet, kind boy I had met all of those years ago."