A high-level Iraqi delegation is expected in Ankara for key talks aimed at stopping attacks by Kurdish fighters based in northern Iraq.
In unusually blunt comments, the Turkish foreign minister has said the Iraqis must come up with concrete proposals for ending the crisis.
The talks come amid intense diplomatic pressure for Ankara to show restraint.
The Turkish military has already been carrying out attacks against Kurdish rebels near its border with Iraq.
It has threatened to mount a ground offensive across the border to flush out fighters from the banned PKK group if diplomatic efforts fail.
Turkish officials have said Thursday's talks could be the last chance.
Turkish Foreign Minister Ali Babacan said Turkey was "expecting them to come with concrete proposals and otherwise the visit will have no meaning".
"We need more than words," Mr Babacan said.
"We said that preventing the PKK from using Iraqi soil, an end to logistical support and all PKK activities inside Iraq and closing of its camps are needed.
"We also said its leaders need to be arrested and extradited to Turkey."
Raids
In recent dayshas been building up its military presence on the border with Iraq, while PKK rebels have stepped up their attacks against Turkish troops.
On Wednesday, Turkey's semi-official Anatolia news agency said Turkish jets had bombed PKK rebel positions.
The raids followed an attack by PKK rebels on Sunday in which 12 Turkish soldiers were killed.
The Turkish military also says eight soldiers are missing.
Iraqi Prime Minister Nouri Maliki said on Tuesday he would work to limit the PKK's activities, and that the group's offices in Iraq would be closed.
There are thought to be about 3,000 PKK rebels based in Iraq. They have been blamed for a number of cross-border raids.
Turkey, the US, and the EU describe the PKK as a terrorist organisation.
Turkish leaders have come under intense pressure from the public and the media to use force.
(BBC News)