TJ Jackson -- Katherine WANTED ME to Take the Kids

Katherine Jackson SUPPORTED TJ Jackson's efforts to obtain temporary guardianship of Michael Jackson's 3 children ... so says TJ in court docs obtained by TMZ.

TJ filed the docs with the court before today's hearing -- and in the papers, TJ claims Katherine was being manipulated by family members who were hellbent on controlling Katherine.

In fact, TJ claims one of his aunts -- either Janet or Rebbie -- arranged for a person to IMPERSONATE A DOCTOR to convince Katherine to blow off a concert series and instead fly with her conspiratorial children to Arizona.

TJ claims he had been assisting with the care of MJ's children since MJ died ... and even before Katherine disappeared, she placed them in his care.

According to the docs, TJ claims he finally spoke with Katherine on July 24 -- and during the conversation, she "indicated to me that she supported me in taking steps that I deemed appropriate to protect [MJ's children]."

TJ was eventually awarded temporary guardianship over Paris, Prince and Blanket.