[en] A contact interaction analysis is presented to search for new phenomena beyond the Standard Model in deep inelastic e^±p →e^± hadrons scattering. The data are collected with the H1 detector at HERA and correspond to integrated luminosities of 0.909 pb^-1 and 2.947 pb^-1 for electron and positron beams, respectively. The differential cross sections dσ/dQ² are measured in the Q² range between 160 GeV² and 20,000 GeV². The absence of any significant deviation from the Standard Model prediction is used to constrain the couplings and masses of new leptoquarks and to set limits on electron-quark compositeness scales and on the radius of light quarks. (orig.)