The non-governmental organisation Human Rights Watch (HRW) says the government has failed to assist hundreds of thousands of displaced people from returning to their homes in the south-east.
The group says the issue directly affects more people in Turkey than any other human rights problem.
Sunday's poll is expected to be one of the most unpredictable and dramatic elections in the country's recent history.
According to the opinion polls, many of the well-established parties are faring badly and may not even reach the overall 10% of votes needed to win parliamentary seats.
Last week, the authorities tried to ban the popular Justice and Development Party (AK) led by Recep Tayyip Erdogan, who himself is barred from parliament, but continues to lead the party.
Displaced
HRW says that up to a million Kurds are now living in miserable conditions in cities across Turkey, hundreds of kilometres from their homes.
Many villages in the south-east were ordered to be evacuated by the Turkish security forces during the 15-year war against Kurdish guerrillas.
The government is refusing to allow them to return unless they sign papers freeing the state from any responsibility.
Villagers complain particularly about so-called "village guards" - men who occupy the village and harass or attack those who try to reclaim their property, says the BBC' Ankara correspondent Jonny Dymond.
Human Rights Watch has called on Turkey to set up a proper planning process for the return of those displaced, and to take steps to return villages to the condition they were in when they were evacuated or abandoned.