The Turkish central bank sold $1.3 billion dollars on Wednesday, market sources said, in a test of wills with the market to hold up the lira but Turkey's borrowing rate rose sharply.
The central bank has sold a total of 3.55 billion dollars since Monday when it announced urgent and "strong" action to defend the currency and contain overheated bank lending.
In afternoon trading on Wednesday, the lira was being quoted at 1.9510 to the dollar from 1.9498 on Tuesday.
The bank had announced its measures on Monday as soon as the lira fell to a record low level of 1.9740.
On Wednesday the central bank sold $1.3 billion in six auctions -- $50 million, $150 million, $150 million, $150 million, another $150 million and $650 million.
The bank had begun its intervention by selling $2.25 billion on Monday. It did not intervene on the foreign exchange market on Tuesday.
On the government debt market, Turkey's 10-year borrowing rate surged to 9.23 percent on Wednesday -- the highest for more than a year.
"We are living extremely volatile times in international markets. I can easily say that the reaction in local yields has reached levels beyond fundamentals," Sengul Dagdeviren at ING Bank based in Turkey told AFP.
But she said that was not a danger signal for Turkey as the public debt level continues to fall and with the Turkish Treasury having completed more than half of the year's domestic borrowing needs.
"In May, there was enough demand in local bond auctions, so we might expect current high yields attract investors again in July" when the Treasury borrows another 11.8 billion lira, she added.
The central bank said Monday it would pursue the new measures for as long as the lira was under pressure.
But market analysts were immediately sceptical that this policy would work for long.
A key factor is expectation that the US Federal Reserve central bank will begin winding down its easy money measures. This has caused investors to pull money out of bond markets in emerging economies, pushing up borrowing rates.
Capital Economics economist Neil Shearing expressed doubts the efforts would work.
He noted that the lira had fallen by about 10.0 percent since the beginning of May, and that inflation in June was 8.3 percent compared with the bank's year-end target of 5.0 percent.
The bank's "firepower is limited", he said putting its foreign currency reserves available for buying the lira at about $45 billion.
Shearing argued that "the lira is likely to fall further over the next year or so" and interest rates were likely to rise.
The Turkish economy grew by 2.2 percent in 2012, short of the government forecast of 3.2 percent expansion.
This was a major slowdown from 2010 and 2011 when Turkish growth jumped ahead by 8.9 percent and 8.8 percent respectively.
"We think growth in Turkey is likely to be weaker and more volatile than most seem to expect," Capital Economics said in a research note.
Emerging Turkey is currently the world's 17th-biggest economy and sets its sights high to rank among the top 10 within a decade.
But analysts say the economy is likely to take a hit from the recent unrest as well as external financing conditions.
Last month, the ruling Justice and Development Party (AKP) was shaken by nationwide demonstrations, which Prime Minister Recep Tayyip Erdogan blamed various groups, including what he called an "interest rate lobby."
This was a reference to pressure for interest rates to rise to support the currency.
On May 16, the central bank had cut its main interest rate by half a percentage point to 4.5 percent to boost the slowing economy.
Global ratings agency Fitch said in a statement that Turkey presents "more of a conundrum."
Fitch warned that "prolonged social unrest, poorly handled, could deter tourism, exacerbate short-term capital outflows, drive-up inflation and damage economic growth, potentially putting Turkey's sovereign rating at risk."
About 14 years ago, Turkey was crippled by a financial crisis and had to restructure its economy in return for help from the International Monetary Fund. It has just finished repaying those loans.