  The hadronic reaction pp --> Sigma+ K0 p was measured exclusively at a beam
momentum of 2.95 GeV/c using the TOF detector at the COSY storage ring. A
narrow peak was observed in the invariant mass spectrum of the K0 p subsystem
at 1530 +- 5 MeV/c2 with a significance of 4 - 6 standard deviations, depending
on background assumptions. The upper limit of 18 +- 4 MeV/c2 (FWHM) for its
width is given by the experimental resolution. The corresponding total cross
section is estimated to be about 0.4 +- 0.1(stat) +- 0.1(syst) microbarn. Since
a resonance in this subsystem must have strangeness S = + 1 we claim it to be
the Theta+ state for which very recently evidence was found in various
experiments.
