Ankara - Turkey warned on Wednesday it would retaliate if any of its 80 nationals seized by an al-Qaeda splinter group during a lightning advance in northern Iraq, were harmed.
The hostages include special forces soldiers, diplomats and children.
Ambassadors of the Nato defence alliance held an emergency meeting in Brussels at Turkey's request. Prime Minister Tayyip Erdogan held talks with President Abdullah Gul, his intelligence chief and the chief of general staff and talked to US Vice President Joe Biden about the developments.
Sunni insurgents from the Islamic State in Iraq and the Levant (ISIL) seized 49 people from the Turkish consulate in the city of Mosul early on Wednesday, including the consul general, family members and Turkish special forces.
The militants are also holding 31 Turkish truck drivers hostage at a power station in Mosul, abducted on Tuesday as ISIL seized Iraq's second biggest city in a show of strength against the Shi'ite-led government in Baghdad.
The rapid advance of ISIL, which overran the Iraqi city of Tikrit on Wednesday and closed in on Iraq's biggest oil refinery, poses an additional threat to Turkey, which is already dealing with the group's seizure of patches of territory just over its southern border in Syria.
"Right now we're engaged in calm crisis management, considering our citizens' security," Davutoglu said in New York after cancelling meetings at the UN to return to Turkey.
"This should not be misunderstood. Any harm to our citizens and staff would be met with the harshest retaliation," he told reporters in comments broadcast on Turkish television.
Turkey has close trade and political links with the Kurdish-controlled area to the north of Mosul that has not, for the moment at least, been targeted by ISIL. It sees a particular role in protecting the interests of the Turkmen ethnic minority in that area.
"Certain militant groups in Mosul have been directly contacted to ensure the safety of diplomatic staff," a Turkish government source said, adding that the Turkish authorities had confirmed that the hostages were unharmed.
The truck drivers, who were abducted by ISIL militants while they were delivering diesel, were being held at a power plant in the Gyarah region of Mosul and efforts to ensure their release were also under way, officials said.
Davutoglu said he had called for the evacuation of the consulate in Mosul several days ago, but that the situation on the ground had been too dangerous for that to take place.
He said on his Twitter account late on Tuesday, after the truck drivers were taken, that the necessary measures had been taken for the safety of the Turkish consulate in Mosul.