By Ian Youngs
Music reporter, BBC News
The fans say they gave letters to Jackson on the night before he died
A group of Michael Jackson fans are planning to protest about a new film showing his final weeks, claiming it covers up his declining health.
Some are planning to hand out leaflets later at simultaneous global premieres of This Is It, a movie made by piecing together concert rehearsal footage.
A small circle of loyal followers say they saw his health go downhill.
Talin Shajanian, from Los Angeles, said: "A couple of weeks before he passed, we saw him change drastically."
Ms Shajanian was one of a number who waited outside the venues where he was rehearsing in the city while preparing for his gigs at London's O2 Arena.
She had been following Jackson since 2003 and gained his trust, along with other devotees, speaking to him on a regular basis, she said.
She told BBC News that fans saw the star change "from being excited about doing the shows to being concerned and not happy with the way things were going, and under a lot of pressure".
"He shared this with us, the pressure that he felt, the concerns that he had," she said.
"He specifically said he was only one person and only had a certain amount of energy to give, that so much was expected of him for these shows."
She said the star was "unusually thin" when the fans last saw him.
"We were expecting him to bulk up, to put on weight for the concerts like he had in the past, and that wasn't happening."
They say they were so concerned that 20 followers wrote letters to the singer imploring him to take care of himself, which they gave him the night before he died.
The dedicated fans, who have set up a campaign called This Is Not It, are accusing concert promoter AEG Live of putting too much pressure on the star and failing to give him adequate medical supervision
They are planning to hand out flyers at many of the 15 simultaneous global premieres on Tuesday and Wednesday. But they are not calling for a boycott of the film.
A spokesman for AEG declined to comment.
Concert choreographer and director Kenny Ortega recently said of Jackson: "Was he slight? Yes. Was he frail? At times.
"But we had a very strong and excited, happy and determined Michael. He wanted to do this more than anything he's ever wanted to do... That's the truth. It really is."
Jackson died two weeks before he was due to return to the stage in London
In another interview, Mr Ortega said: "I think he was eating as much as he thought he needed to. I wished he would have eaten more. I was always making sure there was plenty of food around."
An autopsy found that the 50-year-old star weighed 136lb (9st 10lb) when he died, and had a strong heart but inflamed lungs.
The Los Angeles coroner disclosed in August that Propofol and the sedative Lorazepam were the "primary drugs responsible for Mr Jackson's death".
A statement from Sony Pictures, which is releasing the film, said: "Michael Jackson's This Is It is a celebration of Michael and his music and the film will demonstrate to fans around the world that he was an artist like no other who was passionately creating a one-of-a-kind concert experience.
"We believe his fans will be grateful for the rare opportunity to see Michael's creativity in action as he prepared and rehearsed for his upcoming London concerts."