(Reuters) - Indian drugmaker Ranbaxy Laboratories (>> Ranbaxy Laboratories Limited) posted a loss for the second straight quarter, hurt by foreign exchange charges and a one-time write-off related to one of its plants under an import ban by the U.S. health regulator.

Net loss in July-September was 4.5 billion rupees (45.4 million pounds) from a profit of 7.5 billion rupees a year earlier, it said. Ranbaxy is 63.5 percent owned by Japan's Daiichi Sankyo Co (>> DAIICHI SANKYO COMPANY, LIMITED).

The company incurred a forex charge of 3.6 billion rupees in the latest quarter, while the year-ago results included a forex gain of 3.93 billion rupees.

Sales rose 3 percent to 27.5 billion rupees during the quarter.

The U.S. Food and Drug Administration imposed an import alert last month on Ranbaxy's factory in Mohali in northern India, saying the plant had not met "good manufacturing practices".

All three Ranbaxy plants in India dedicated to the U.S. market, which accounts for more than 40 percent of its sales, have now been barred from shipping to the United States.

The company had pleaded guilty in May to U.S. felony charges related to drug safety and agreed to a record $500 million in fines. After falling more than 40 percent in the months afterwards, the share price had started to inch back up.

(Reporting by Aradhana Aravindan and Swati Pandey in MUMBAI; Editing by Prateek Chatterjee)