Turkey's pro-Kurdish party has filed a complaint with the high electoral board accusing President Recep Tayyip Erdogan of breaching rules that require him to be impartial.

The People's Democratic Party, or HDP, asked the board on Tuesday to issue a warning to Erdogan and to ensure that he remains neutral in the run-up to Turkey's June 7 elections.

Erdogan headed the ruling AKP party until his election as president in August. He wants Turkey to switch to a system where the president yields executive powers and has increasingly been appearing at large rallies where he openly criticizes opposition parties.

Erdogan insists he is at an "equal distance" to all parties but says he has a special affection toward the AKP.