US Secretary of State Condoleezza Rice visits Turkey on Friday in a bid to dissuade Ankara from launching a cross-border military strike against Kurdish rebels in northern Iraq.
Turkey accuses the regional Kurdish government in northern Iraq of harbouring and aiding fighters from the separatist Kurdistan Workers' Party (PKK).
Both Baghdad and Washington strongly oppose any unilateral Turkish action in northern Iraq on the grounds that it would destabilise the only relatively calm region of the war-torn country.
The PKK uses bases in the mountainous region for cross-border attacks as part of its 23-year campaign for self-rule in Turkey's mainly Kurdish southeast.
Turkey has reportedly massed up to 100,000 troops on the border with Iraq and has threatened a military incursion to strike at the PKK bases unless Baghdad and Washington make good on promises to crack down on the rebels.
The White House has offered Ankara "actionable intelligence" on the PKK.
Iranian Foreign Minister Manouchehr Mottaki arrived in Ankara on Thursday night to meet Turkish Foreign Minister Ali Babacan, one day after Baghdad appealed for Tehran's help to defuse the crisis.
Rice, Mottaki, UN Secretary General Ban Ki-moon and Iraqi Prime Minister Nuri al-Maliki are all scheduled to attend a ministerial conference of Iraq's neighbours and major Western powers in Istanbul today and Saturday.
"We have no time to lose. All instruments -- diplomatic, political, socio-cultural and military -- are on the table," Babacan said, adding that Ankara might opt to restrict flights to northern Iraq.