JHK imaging photometry is reported of an area of approximately 2'x3' centred on the far infrared source NGC 6334 I with limiting magnitudes J=18.3, H=17.8 and K=16.2. More than 224 sources were detected in K-band, increasing by a factor of more than seven the number of objects found in previous near-IR surveys. Most of the sources are located in an area of about 3500 square arcsec centered around the massive young stellar object Irs1, which ionizes the compact HII region NGC 6334 F. The location of these sources and the analysis of the colour-colour and colour-magnitude diagrams suggest the presence of an embedded and young stellar cluster of size ~70" (0.6pc), and stellar density of about 1200pc-3. The star formation efficiency is estimated to be SFE=~0.25. Only a few of the most luminous stars of the cluster were found to show large near-IR excesses but this may be due to the non-detection, at the shortest wavelength, of the majority of the highly reddened cluster members. The extinction of the region is very variable with a maximum of AV>70 in Irs2 while the average is =~40. Very close to the position of an H2O maser associated with NGC 6334 I(N), a contracting core at an earlier evolutionary stage, we found six very red sources, one of which is a small and diffuse nebula seen only at 2.2μm. Finally, the older and developed HII region NGC 6334 E was found to be probably ionized by a small cluster of at least 12 B0-B0.5 ZAMS stars. For a description of the JHK photometric system, see e.g. (1 data file).