BigTiff TIFF64 File Export

[tsiolkovsky]

I have an xcf project which is so large that when it exports to tiff it fails due to reaching the tiff file limit size. This is due to the 32bit tiff file size limit. I would like to be able to export my image to BigTiff, the 64bit tiff file type. Currently, I am able to work around this by cropping the file into pieces, saving them each as 32bit tiff files, and then using ImageMagick to append the files into a TIFF64 BigTiff output file.

How do I get GIMP to export as TIFF64?

Thanks