ANKARA (AP) ― Turkey deepened its rift with Israel on Monday by vowing to work for the recognition of a Palestinian state at the United Nations and by saying it has notified high-level Israeli diplomats they have two days to leave the country.

Late last week, Turkey expelled the Israeli ambassador after Israel refused to apologize for the botched Israeli raid on a Gaza-bound protest flotilla that killed nine pro-Palestinian activists last year. Israel has expressed regret for the loss of lives.

A U.N. report released last week called the Israeli raid “excessive and unreasonable,” but also said Turkey and flotilla organizers contributed to the deaths.

The dispute has brought relations between the once-close allies to the verge of collapse, and injected a new element of instability into an already volatile region.

Turkey said Monday it has notified Ella Aphek, the Israeli Embassy’s deputy head of mission, that she and other senior Israeli diplomats must leave by Wednesday now that Turkey has decided to downgrade its diplomatic ties with Israel to the level of second secretary.

Foreign Minister Ahmet Davutoglu said Monday that Turkey will work to lobby other nations “until we obtain the highest number of votes” for a plan by Palestinians to seek recognition as a state at annual meeting of world leaders at the U.N. General Assembly beginning on Sept. 20.

On Saturday, Davutoglu said Turkey would start procedures to challenge Israel’s naval blockade of Gaza at the International Court of Justice in The Hague, Netherlands.

The United States has indicated it will veto any Palestinian statehood vote in the absence of a negotiated Israeli-Palestinian peace deal.

Palestinians hope a U.N. vote in their favor would isolate Israel and put heavy pressure on the Israelis to withdraw from captured territories.

“Recognition of a Palestinian state is not a favor for the Palestinians, it is the Palestinian people’s most natural right and our debt to them,” Davutoglu told a news conference with Palestinian President Mahmoud Abbas’ adviser, Nabil Shaath.

“It is time to pay the debt.”

Also Monday, the fallout from the Israeli-Turkish rift sparked a spat over airport security, with Israeli air passengers complaining they were harassed and intimidated Monday at Istanbul airport and Turkish air passengers making similar claims about their treatment in Tel Aviv.

A Turkish Foreign Ministry official said that Turks flying back to Turkey from Tel Aviv complained about being mistreated in Israel, prompting Turkish customs police to “retaliate” with more stringent security measures against Israeli passengers.

The official said police “searched the Israelis’ passports more rigorously and delayed the procedures as much as possible.” He said police acted on their own initiative.

The Turkish official spoke on condition of anonymity in line with ministry regulations that bar officials from speaking to journalists without prior authorization.

Reports of airport harassment first emanated from Turkey, where media reported that Turkish passengers on a Turkish Airlines flight from Tel Aviv to Istanbul said they were singled out for particularly thorough searches and questioning.

Eyup Ensar Ugur, a Turkish tour guide on the flight, told The Associated Press that media reports about harassment were exaggerated.

“They questioned us repeatedly and searched our bags and bodies in detail but any harassment is out of question,” Ugur said in an interview. “I was asked to remove my top, my pants were on but had to unzip them. One official searched my body by hand and a detector,” Ugur said.

The plane made an emergency landing in the Mediterranean city of Antalya to remove a passenger who felt sick, he said. There, one Muslim Turk and another Turkish Jew argued with some other Turks about the necessity of the strict security check, Ugur said. That led to a scuffle in the airport that Turkish police quelled, he said.

Later Monday, dozens of Israeli passengers on flights between Tel Aviv and Istanbul reported that Turkish security officials at Ataturk International Airport briefly took their passports and questioned them, a passenger and the Israeli Foreign Ministry said.