Résumé : The breakup of 10,12Be into He clusters has been studied using the p, 12C(12Be,6He,6He) and 12C(12Be,4He,6He) inelastic scattering and two neutron transfer reactions with a 378 MeV 12Be beam incident on 12C and (CH2)n targets. Evidence has been found for three new states in 10Be at excitation energies of 13.2, 14.8, and 16.1 MeV, which may be associated with a 4He+6He cluster structure. The evidence for He cluster states in 12Be in the excitation energy range 12 to 25 MeV is also discussed.