The Turkish lira lost over one percent in value to trade at 3.97 to the dollar late morning, testing the never-before-reached 4.0 ceiling, before rallying slightly to 3.95 in the early evening.
The lira is the worst-performing emerging markets currency in the world this year, losing 12.38 percent in value against the greenback since January.
The latest drop followed the delay on Monday of a scheduled trial in the United States of Turkish-Iranian gold trader Reza Zarrab and Mehmet Hakan Atilla, the deputy chief executive of Turkish lender Halkbank, accused of defying US sanctions on Iran.
The trial has caused anger in Ankara, with the Turkish government on Monday calling the case "political".
Government spokesman and Deputy Prime Minister Bekir Bozdag claimed the suspects were being held like hostages and described the trial as a "plot against Turkey".
New York Judge Richard Berman announced that jury selection, which had been set to begin Monday, was delayed until November 27. Opening statements are now scheduled for December 4.
There are concerns over the impact of the case on US-Turkey relations and the possibility of fines against Halkbank in the event of a guilty verdict.
The NATO allies' ties have already been strained over Washington's support for a Syrian Kurdish militia that Turkey views as a "terror" group as well as the failure to extradite a Pennsylvania-based Muslim cleric blamed for last year's failed coup.
- 'Rate tightening needed' -
Meanwhile, the Turkish authorities also announced new regulations in the "merger, division, transfer of assets and exchange of bank shares" in the Official Gazette on November 16, state-run news agency Anadolu reported.
But Deputy Prime Minister Mehmet Simsek on Monday denied claims that this meant Halkbank would be absorbed into another bank:
As the lira weakened, the Turkish central bank announced that banks would not be able to borrow funds overnight in the interbank money market from Wednesday.
Gokce Celik, chief economist at QNB Finansbank, said the issues pressuring the lira included the deteriorating inflation outlook, widening current account deficit and diplomatic risks from the Zarrab-Atilla case.
Taken together, these "necessitate interest rate tightening," she said, forecasting stubbornly high inflation of around 10 percent.
However, the central bank may feel constricted from making any drastic move in raising rates after President Recep Tayyip Erdogan lashed out at it last week again over its refusal to cut interest rates.
He said this was causing high inflation, a statement that flew in the face of conventional economic wisdom.
Usually, inflation should go down as interest rates are raised as this softens demand and weakens money supply growth in an economy.
- 'Difficult to forecast lira' -
The lira has been on a trend of sharply losing value against the dollar since April, when Erdogan narrowly won a referendum on expanding his powers.
Turks have grown accustomed to seeing the depreciation of their currency which was trading at 1.78 lira to the dollar at the start of 2013.
But Inan Demir, economist at Nomura International, said it was "rather difficult" to forecast where the lira would be in 2018.
"The obvious remedy to stop the depreciation is to restore real interest rates to levels that would make the Turkish lira attractive for foreign investors again," he told AFP.
But he said that Erdogan's repeated onslaughts on the central bank for not pursuing a sufficiently expansionary monetary policy tied the hands of the nominally independent institution.
"Rate hikes face obvious political obstacles that will not be easy to overcome," he said.
Celik added it was a "non-negligible possibility" that the central bank would hold an emergency meeting before a scheduled monetary policy committee meeting on December 14.