Turkish President Recep Tayyip Erdogan says recent election results in Istanbul should be annulled over irregularities that include the alleged unlawful appointment of some officials overseeing the ballot boxes.

Speaking to reporters on his return from a trip to Moscow, Erdogan said his ruling party would continue to use its right to appeal and would track alleged irregularities "until the end."

Erdogan said people who are not civil servants unlawfully headed ballot boxes in some areas.

His remarks were published by pro-government Yeni Safak newspaper on Wednesday.

Erdogan's party suffered a major setback in the country's March 31 local elections. Opposition candidates won in Turkey's capital, Ankara, and squeezed out Erdogan's party in Istanbul.

The party says it plans to seek a re-run of the Istanbul vote due to irregularities.