The mechanism and the region of generation of variable continuum emission are poorly understood for radio-loud AGN because of a complexity of the nuclear region . High-resolution radio VLBI ( very long baseline interferometry ) observations allow zooming into a subparsec-scale region of the jet in the radio-loud galaxy 3C 390.3 . We combined the radio VLBI and the optical data covering the time period of 14 years to look for a link between optical flares and parsec-scale jet . We identify two stationary and nine moving radio features in the innermost subparsec-scale region of the jet . All nine ejections are associated with optical flares . We found a significant correlation ( at a confidence level of > 99.99 \% ) between the ejected jet components and optical continuum flares . The epochs at which the moving knots pass through the location of a stationary radio feature and the optical light curve reaches the maximum are correlated . The radio events follow the maxima of optical flares with the mean time delay of 0.10 \pm 0.04 years . This correlation can be understood if the variable optical continuum emission is generated in the innermost part of the jet . A possible mechanism of the energy release is the ejection of knots of high-energy electrons that are accelerated in the jet flow and generate flares of synchrotron continuum emission in the wide range of frequencies from radio to X-ray bands . In this scenario , the beamed optical continuum emission from the jet and counterjet ionizes a gas in a subrelativistic outflow surrounding the jet , which results in a formation of two outflowing conical regions with broad emission lines ( in addition to the conventional broad line region around the central nucleus ) .