Parliamentarians from the Republican People's Party (CHP), the Peoples' Democratic Party (HDP) and Iyi Party told Reuters they had filed thousands of objections to the voter records, including voters registered in areas where they no longer live.
Results of the March 31 municipal elections are expected to be close. As the economy sours President Tayyip Erdogan's AK Party, which has dominated Turkish politics since 2002, faces losing some large cities including the capital Ankara.
The CHP and HDP said the irregularities were mainly in districts where the AK Party previously lost by a small margin. An AK Party official said its opponents were wrongly trying to blame it, adding that Erdogan's party would suffer most.
"The opposition parties are trying to create the perception that we are organising this," Recep Ozel said, adding that the AK Party had filed many objections as well. "We are the biggest victims here," he said.
CHP parliamentarian Onursal Adiguzel said 6,389 voters over the age of 100 had been identified among the lists of registered voters and that the party had asked the High Electoral Board (YSK) to investigate.
Those include 165-year-old Ayse Ekici, supposedly born in the 19th-century reign of Sultan Abdulmecid who introduced the first Ottoman paper banknotes. Ekici was registered as not having voted before. Another improbable voter is named simply as Zulfu, aged 149.
The CHP said that voter numbers in some districts rose significantly since presidential elections in June. The most dramatic increase was in the Orta district of Turkey's northern Cankiri province, where they increased 95 percent.
Heavy anomalies could be seen in areas where the AK Party lost by a small margin in previous elections, Adiguzel said.
"We found 40 voters registered in the apartment of an Uskudar municipal parliament member," he said, referring to the Istanbul district, where the AK Party last won by a small margin.
Erdogan said last week that nearly 1.5 million people had changed districts since elections last June, adding that the AK Party was unable to find the records of more than 500,000 of its members on voter lists.
OBJECTION DEADLINE
Iyi Party general executive board member Burcu Akcaru said the party had objected to around 126,000 voter records.
"We have determined 80 people with 45 different last names registered in one apartment in Bitlis," she said, referring to the southeastern province. Some voters were registered in disused buildings, she said.
Akcaru said the electoral board had rejected a request to extend the deadline for objections to voter lists, but the AK Party's Ozel said the board had no authority to do that. The YSK referred questions to individual district electoral boards.
The pro-Kurdish HDP proposed forming a parliamentary commission to investigate the abnormalities, citing an apartment in the southeastern province of Hakkari with 1,108 registered voters, and another in Mardin with 506.
HDP parliamentarian Meral Danis Bestas said some voters told the party that their records had been deleted. She said the HDP had filed tens of thousands objections and sought to re-register voters whose records were deleted.
"This is not a normal, fair election, in which everyone is in an equal race," she said.