President Recep Tayyip Erdogan blamed the US ambassador to Turkey on Tuesday for a diplomatic crisis between the two countries and said Ankara no longer considered him Washington's envoy.
In a blunt and personal attack on outgoing ambassador John Bass, Mr Erdogan suggested Mr Bass acted unilaterally in suspending visa services in Turkey after the arrest of a US consulate worker, and said "agents" had infiltrated US missions.
The US State Department defended Bass, saying he had the "full backing" of the US government and his actions were co-ordinated with the State Department, White House and National Security Council.
"Our ambassadors tend not to do things unilaterally," State Department spokeswoman Heather Nauert told a briefing. "We have a very close co-ordination and co-operation with our ambassadors," she added, saying Mr Bass had done "a terrific job in Turkey".
The dispute has plunged already fragile relations between the two NATO allies to a new low after months of tension linked to the conflict in Syria, last year's failed military coup in Turkey, and US court cases against Turkish officials.
The US embassy said on Sunday night it was suspending visa services while it assessed Turkey's commitment to the safety of its missions and its staff, a message reiterated in a video released by Mr Bass late on Monday.
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"An ambassador in Ankara taking decisions and saying he is doing so in the name of his government is strange," Mr Erdogan said. "If our ambassador did this, we wouldn't keep him there even a minute."
The embassy said allegations that the arrested employee had links to Fethullah Gulen, a US-based Muslim cleric blamed by Ankara for orchestrating the failed coup against Mr Erdogan last year, were baseless.
Ms Nauert said Turkey, which has arrested two local US embassy staff members this year, summoned a third local staff member for questioning over the weekend, a "deeply disturbing" move. Some of those targeted were responsible for law enforcement co-ordination between the countries, she said.
"Being able to have close security co-operation, especially with a NATO partner, is incredibly important," Ms Nauert said. "And when they start arresting, detaining our people, our people who are responsible for law enforcement co-ordination, that is a … major concern of ours. And so that is why we took these steps."
But Mr Erdogan said the arrest, and a police request to question a second consulate employee, showed "there is something cooking in the US consulate in Istanbul … How did these agents infiltrate the US consulate?"
He said Mr Bass, who is due to leave the country within days to take up a posting in Afghanistan, had been making farewell visits to government offices.
"But our ministers, parliament speaker and myself did not accept and will not accept his request because we do not see him as a representative of the United States," Mr Erdogan told a televised news conference during a visit to Belgrade.
Prime Minister Binali Yildirim said the visa suspension had punished citizens of both countries, and accused Washington of taking an emotional and inappropriate step against an ally.
"You are making your citizens and ours pay the price," he said. "We call on the United States to be more reasonable. The issue must of course be resolved as soon as possible," he said, describing US behaviour as "unbecoming" of an ally.
In a speech in Ankara to ruling AK Party parliamentarians, Mr Yildirim also defended Turkey's decision to retaliate with its own visa suspension after the US embassy announcement.
"Turkey is not a tribal state, we will retaliate against what has been done in kind," he said.