The terms of several LG bodies were extended until May 15 by the president previously.
Tenures of certain LG bodies, including the Colombo municipal council, will be completed in October.
The spokesman also said LG elections would be held under the first-past-the-post system, and that the SLFP would give priority to discipline when giving nominations.
A majority of SLFP LG members are Mahinda Rajapaksa loyalists and many are accused of violating party discipline.