Is it possible to "properly" indent inside latex fragments?

[Alain.Cochard@unistra.fr]

Hello.  

This is what I obtain if I type each line followed by <Enter> and then
<TAB> in an org file:

* foo
  \begin{displaymath}
  \begin{split}
  a &= b \\
  &+c  
  \end{split}
  \end{displaymath}

If I highlight everything and use 'M-x indent-region' or 'M-x
org-indent-region', it does not change.

Instead, what I would like to get is:

* foo
  \begin{displaymath}
    \begin{split}
      a &= b \\
      &+c
    \end{split}
  \end{displaymath}

(That specific indentation for the latex instructions is what I obtain
within a .tex file.)

Is it possible?  
Thank you.

(I did spend quite some time searching for a solution...)

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