It is shown that escaping of solar flare energetic protons into interplanetary space as well as their relation to the flare gamma-ray emission depend on the parameter/~ = 8np/B~, where p is the pressure of hot plasma and energetic particles and Bo is the magnetic field in a flaring loop. If/3 ~ 1, the bulk of the energetic protons escape to the loss cone because of diffusion due to small-scale Alfv6n-wave turbulence, and precipitate into the footpoints of the flaring loop. The flare then produces intense gamma-ray line emission and a weak flux of high energy protons in interplanetary space. If 8>//, ---0.3-1.0, then fast eruption of hot plasma and energetic particles out of the flaring loop occurs, this being due to the flute instability or 'magnetic-field-plasma' nonequilibrium. The flare then produces a comparatively weak gamma-radiation and rather intense proton fluxes in interplanetary space. We predict a modulation of the solar flare gamma-ray line emission with a period ~< 1 s during the impulsive phase that is due to the MHD-oscillations of the energy release volume. The time lag of the gamma-ray peaks with respect to the hard X-ray peaks during a simultaneous acceleration of electrons and protons can be understood in terms of strong diffusion.