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The executors of Michael Jackson's lucrative estate say they are concerned about the welfare of the superstar's children and their current legal guardian, Michael's mother Katherine Jackson. 

The managers of the King of Pop's estate issued their concerns Tuesday in a letter to fans amid a dispute among Jackson family members over the validity of Michael Jackson's will -- which leaves everything to Katherine and his three children, Paris, Prince Michael and Blanket.

"We are acutely concerned about the welfare of Mrs. Jackson, and most particularly with Michael's minor children. We are concerned that we do what we can to protect them from undue influences, bullying, greed, and other unfortunate circumstances," reads the letter signed by co-executors John Branca and John McClain.

RELATED: Cops Called to Jackson Home After Possible Battery

The statement adds: "We believe measures are being put in place that will help protect them from what they are having to deal with. We take these matters very seriously and will continue to report on them as appropriate."

The letter came just hours after Los Angeles Sheriff deputies were called to Katherine's Calabasas, CA home after a physical altercation between family members that is being investigated as a possible battery. Sheriff's spokesman Steve Whitmore confirmed that a physical altercation between unnamed individuals took place on the property, but no arrests were made and the matter is being further investigated. 

In a related development, sources connected to the situation tell ET that Michael's siblings Randy and Jermaine have asked his estate to help pay for their child support after apparently falling behind on payments. The source say the requests for financial help came over the past year but were immediately denied by the estate.

RELATED: Katherine Jackson Safe After Reported Missing