According to Berg & Corner (2005) Flora Malesiana Moraceae- FicusFicus obliqua is a common giant strangling fig of New Guinea and Northern Australia  found east into the Pacific including New Caledonia, Fiji, Tonga and Samoa.  The nearest location this fig occurs to Borneo is Ternate in the Moluccas. This fig was probably brought to Brunei as an ornamental or bonsai.

Photo credit Tuan Husini thanks to Shavez Cheema