Résumé
Very high energy gamma-ray emission has been recently detected by H.E.S.S. from the direction of associations between supernova remnants and molecular clouds. In such associations dense molecular clouds may reveal accelerated cosmic rays in the vicinity of supernova remnant forward shocks. Hadronic interactions could explain part or all of the observed gamma-ray fluxes. The discovery of a new VHE gamma-ray source, HESS J1923+141, coincident with the supernova remnant W51C, is reported. Amongst possible associations for this source is a shocked molecular cloud.