We present analysis of plasma parameters during the initial phase of the 12 June 2010 flare (SOL2010-06-12T00:57). Peculiarity of the flare was detection of gamma-emission that is unusual for the such weak and short event. The analysis revealed the flare precursor detected about 5 minute before the flare onset on 94 Å images which spatially coincided with Neutral Line associated Source (NLS) indicated by the non-polarized MW source at 17 GHz (NORH). A comparison of results obtained from microwave (MW) data by the Nobeyama Radio Polarimeter and the Siberian Solar Radio Telescope (the new 10-antenna radio heliograph prototype at 4.6 and 6.4 GHz) and hard X-ray (HXR) observations by the Fermi Gamma-ray Space Telescope reveal presence of accelerated electrons at the initial phase the flare development. The analysis of MW and HXR spectra also confirms presence of accelerated particles. Moreover a good temporal correlation between several lightcurves of HXR energy bands and MW frequencies indicates to generation of both HXR and MW emission by the common populations of accelerated electrons.
Detection of accelerated particles during the initial phase of the flare and SHH (soft-hard-harder) behaviour of the spectra points to several episodes of particle acceleration and confirms the non-impulsive type of the flare evolution.