Context: UV observations of some massive globular clusters have revealed a significant population of very hot stars below the hot end of the horizontal branch (HB), the so-called blue hook stars. This feature might be explained either as a result of the late hot flasher scenario where stars experience the helium flash while on the white dwarf cooling curve or by the progeny of the helium-enriched sub-population recently postulated to exist in some clusters. Previous spectroscopic analyses of blue hook stars in ω Cen and NGC 2808 support the late hot flasher scenario, but the stars contain much less helium than expected and the predicted C, N enrichment could not be verified. Aims: We compare observed effective temperatures, surface gravities, and abundances of He, C, and N of blue hook and canonical extreme horizontal branch (EHB) star candidates to the predictions of the two scenarios. Methods: Moderately high resolution spectra of stars at the hot end of the blue HB in the globular cluster ω Cen were analysed for atmospheric parameters and abundances using LTE and non-LTE model atmospheres. Results: In the temperature range 30 000 K to 50 000 K we find that 35% of our stars are helium-poor (log{{n_He}/{n_H}} < -2), 51% have solar helium abundance within a factor of 3 (-1.5 ⪉ log{{n_He}/{n_H}} ⪉ -0.5) and 14% are helium-rich (log{{n_He}/{n_H}}} > -0.4). We also find carbon enrichment strongly correlated with helium enrichment, with a maximum carbon enrichment of 3% by mass. Conclusions: At least 14% of the hottest HB stars in ω Cen show helium abundances well above the highest predictions from the helium enrichment scenario (Y = 0.42 corresponding to log{{n_He}/{n_H}} ≈ -0.74). In addition, the most helium-rich stars show strong carbon enrichment, as predicted by the late hot flasher scenario. We conclude that the helium-rich HB stars in ω Cen cannot be explained solely by the helium-enrichment scenario invoked to explain the blue main sequence. Based on observations with the ESO Very Large Telescope at Paranal Observatory, Chile (proposal IDs 075.D-0280(A) and 077.D-0021(A)).