A search for stable or long-lived heavy charged particles in e(+)e(-) interactions at energies of 130-136, 161 and 172 CeV has been performed using the data taken by the DELPHI experiment at LEP. The search is based on particle identification provided by the Time Projection Chamber and the Ring Imaging Cherenkov detector. Upper limits at 95% confidence level are derived on the cross-section for heavy long-lived pair-produced charge +/-e and +/-2/3e particles in the range of 0.4-2.3 pb for masses from 45 to 84 GeV/c(2). Within supersymmetric extensions of the Standard Model, long-lived charginos with masses from 45 to 84 (80) GeV/c(2) for high (low) sneutrino masses can be excluded at 95% confidence level. Left-handed (right-handed) long-lived or stable smuons and staus with masses between 45 and 68 (65) GeV/c(2) can be excluded at 95% confidence level. (C) 1997 Elsevier Science B.V.
