Turkey said they would use the meeting with Khalid Mishaal, the exiled supreme leader of Hamas, on Thursday to put forward international demands for the resistance group to renounce violence.
A Turkish Foreign Ministry statement said: "The expectations of the international community following the Palestinian elections will be clearly conveyed during the talks," adding that Hamas had asked to send a delegation to Turkey.
Mishaal is on a tour to muster support from Muslim states to counter Western governments' efforts to step up the pressure on the party that won last month's Palestinian elections.
The Ankara visit, the first of Mishaal's current tour to a non-Arab country, came following an offer by Recep Tayyip Erdogan, the Turkish prime minister, to act as go-between for Israel and the new Palestinian administration.
The talks are likely to upset Turkey's allies, the US and Israel, both of which are seeking to maintain the group's international isolation. Israel has categorically ruled out any talks with Hamas as long as it remains committed to the destruction of the Jewish state.
The Israeli government was infuriated by Vladimir Putin's decision earlier this month to invite Hamas to talks in Moscow.
Turkey, a predominantly Muslim but strictly secular state, has been Israel's main regional ally since 1996 when the two countries signed a military cooperation accord, much to the anger of Iran and Arab countries.
But it also enjoys close relations with the Palestinians and supports their claim for statehood.
Mishaal, who is heading a five-man delegation, was meeting with Turkish diplomats including Ahmet Uzumcu, the Foreign Ministry's deputy under-secretary, and Bozkurt Aran, the head of the ministry's Middle East department.
The Hamas leader, who is based in Syria, has also requested to meet Erdogan, sources said, but it was not immediately clear whether the meeting would take place.
Erdogan has offered to mediate
between Israel and Hamas
Anatolia news agency said the Hamas delegation had not been invited to Turkey through diplomatic channels, while NTV and CNN-Turk news channels said the invitation came from the ruling Justice and Development Party (AKP).
A Turkish official source said both the United States and Israel had been informed of the visit.
Eager for his country to play a more prominent role in the Middle East peace process, Erdogan last month said Turkey was ready to mediate between Israel and Hamas.
But he also urged Hamas to renounce violence and work with Israel.
The US and the European Union have listed Hamas as a terrorist organisation and argue that it must renounce violence and recognise Israel if it wants to form the next government in the Palestinian territories.