How to extract .gtar file?

I have a .gtar file, I wanted to extract it, but it is not getting extracted. Below are the methods I have tried with its output. I supposed to be contained bunch of text files.

-shellsession
$ gtar -xf file.gtar
gtar: This does not look like a tar archive.
gtar: Skipping to next header.
gtar: Exiting with failure status due to previous errors.

$ gtar -xzf file.gtar
gzip: stdin: not in gzip format
gtar: Child returned status 1
gtar: Error is not recoverable: exiting now

$ gunzip -c file.gtar | tar xvf -
gzip: file.gtar: not in gzip format
tar: This does not look like a tar archive
tar: Exiting with failure status due to previous errors

$ tar -xzf file.gtar 
gzip: stdin: not in gzip format
tar: Child returned status 1
tar: Error is not recoverable: exiting now

$ file file.gtar 
file.gtar: HTML document, ASCII text, with very long lines, with no line terminators

Can anyone please suggest some method to extract it?