Self-broadening of the 146.96 nm xenon line and 123.58 nm krypton line is studied in the density range 1-100 amagat (2.7 x 1019 — 2.7 × 1021 at. cm-3). The absorption profile is deduced from reflection experiments by a modified Kramers-Krönig analysis. A detailed discussion of the criteria for validity of available theories is given, allowing the determination of the extent to which the cases studied are related to many-body interactions and/or pure resonance forces. The quasistatic theory, in the nearest neighbour approximation, is shown to be valid for interpreting the far wings. Thus it is possible at increasing density, to underline the specific effect of the various kinds of forces : resonance, Van der Waals and repulsive, and to specify the 1u excited state potential which is found weakly attractive for Xe2 and Kr2