* Q3 profit 3.65 bln rupees vs. est. 9.12 bln rupees
* U.S. sales fall 35 pct
* Profit hit by one-time deferred tax adjustment (Adds details)
Feb 14 (Reuters) - India's largest drugmaker Sun Pharmaceutical Industries Ltd reported a 75 percent plunge in third-quarter net profit on Wednesday as pricing pressures in the United States, its biggest market, hit sales.
Sun Pharma, along with other Indian pharmaceutical companies, has been battling increased competition in the generics market and greater pricing scrutiny in the United States.
The drugmaker has also struggled as some of its products were banned from sale in the United States because the factories that made them did not meet U.S. quality standards. It was also hit by adjustments for U.S. tax reforms in the third quarter.
Its net profit of 3.65 billion rupees ($57 million) for the October-December quarter was its smallest profit in over two and a half years, and well below analysts forecasts of 9.12 billion rupees in a Reuters poll.
The company said its U.S. sales slumped 35 percent to $328 million in the quarter, hurt by lower sales of generic versions of cancer drug imatinib and olmesartan, which is used in the treatment of high blood pressure.
U.S. sales accounted for nearly a third of the company's total sales, which fell 14 percent to 65.9 billion rupees.
The company said its profit was also hit by a one-off deferred tax adjustment of 5.13 billion rupees on account of tax reforms in the United States. ($1 = 64.0800 Indian rupees)
(Reporting by Jessica Kuruthukulangara in Bengaluru; Editing by Edmund Blair and Susan Fenton)