  We report the existence of Griffiths phase (GP) over a wide range of $x$ in
La$_{0.6}$Sr$_{0.4}$Mn$_{1-x}$Co$_x$O$_3$, the solid solution of ferromagnetic
(FM) La$_{0.6}$Sr$_{0.4}$MnO$_3$ and La$_{0.6}$Sr$_{0.4}$CoO$_3$, from
magnetization measurements. In this compound, GP arises due to the quenching of
randomly distributed Co-O-Mn antiferromagnetic bonds in the FM background. In
contrary to divalent doped manganites, GP in the present system can exist
entirely in the metallic state above $T_C$ (for $x$$<$0.10). Based on the
present study, a magnetoelectronic phase diagram is drawn.
