The demonstrators from the All Progressives Congress (APC) converged on the local offices of the Independent National Electoral Commission (INEC) in the state capital, Port Harcourt.
"We are here to register our protest that there was no election in Rivers state yesterday," Rivers state governorship candidate Dakuku Peterside told the crowd.
Peterside alleged that APC supporters across the southern state were "disenfranchised by INEC, working in connivance with (the) PDP (Peoples Democratic Party)".
"INEC in collaboration with (the) Peoples Democratic Party hijacked the materials and were filling them in private homes for the PDP," Peterside claimed.
"Since the results sheets were not available, we did not vote. If there was no voting, there is no way they can declare any result."
Peterside called for the presidential and parliamentary election to be re-held in Rivers on a new date.
Rivers state in the oil-producing Delta is seen as a key battleground for the presidential election, in which APC candidate Muhammadu Buhari is fighting President Goodluck Jonathan of the ruling PDP.
