Dilute nitride InGaAsN layers with high In content have been grown on InAs substrates by liquid phase epitaxy using GaN as a precursor for N in the growth solution. Photoluminescence (PL) was obtained in the mid-infrared spectral range at temperatures between 4 and 300 K. Although Ga increases the InAs bandgap, the strong band anti-crossing effect from the N incorporation resulted in an overall bandgap reduction of 11 meV compared with InAs. The temperature-dependent PL exhibited a complicated behaviour and showed an anomalous increase in intensity from 190K to room temperature. This was due to the formation in a complex defect which behaves as a non-radiative recombination centre and prevents radiative band-band recombination at temperatures <190 K. Above this temperature the PL increases as band-band transitions become allowed. The formation of this defect requires the presence of both Ga and N and becomes de-activated after a high-temperature anneal. Raman spectroscopy confirmed the presence of phonon modes associated with In-N and Ga-N bonds confirming the incorporation of N using liquid phase growth.