We present ground-based 3 \mu m spectra of obscured Asymptotic Giant Branch ( AGB ) stars in the Magellanic Clouds ( MCs ) .
We identify the carbon stars on the basis of the 3.1 \mu m absorption by HCN and C _ { 2 } H _ { 2 } molecules .

We show evidence for the existence of carbon stars up to the highest AGB luminosities ( M _ { bol } = -7 mag , for a distance modulus to the LMC of 18.7 mag ) .
This proves that Hot Bottom Burning ( HBB ) can not , in itself , prevent massive AGB stars from becoming carbon star before leaving the AGB .
It also sets an upper limit to the distance modulus of the Large Magellanic Cloud of 18.8 mag .

The equivalent width of the absorption band decreases with redder ( K - L ) colour when the dust continuum emission becomes stronger than the photospheric emission .
Carbon stars with similar ( K - L ) appear to have equally strong 3 \mu m absorption in the MCs and the Milky Way .
We discuss the implications for the carbon and nitrogen enrichment of the stellar photosphere of carbon stars .