A search for pair-produced leptoquarks has been performed using a sample of $\mbox{e}^+\mbox{e}^-$ collision events collected by the OPAL detector at LEP at $\mbox{e}^+\mbox{e}^-$ centre-of-mass energies from 189 up to 209~GeV. The data sample corresponds to a total integrated luminosity of about 596~pb$^{-1}$. The leptoquarks were assumed to be produced via couplings to the photon and the Z$^0$ and then to decay promptly into a lepton and a quark. The simplifying assumption is made that couplings within a single generation of leptons can exist. No evidence for contributions from leptoquark pair production processes was observed. Lower limits at $95\%$ CL on scalar and vector leptoquark masses are obtained. The existing limits are improved for scalar leptoquarks with a large decay branching ratio to quark-neutrino.