Oct. 3 (Bloomberg) -- National Aluminium Co., India's biggest producer of alumina, resumed full production after the end of a coal shortage that cut output 11 percent last month.

Alumina output fell to 116,000 metric tons from the monthly average of 130,000 tons after heavy rainfall disrupted supplies, Chairman C.R. Pradhan said today in a phone interview. Production returned to full capacity at the start of this month, he said.

A mid-year strike by truckers and rising demand from power- generation companies also resulted in a drop in coal deliveries to National Aluminium. The company sells 64 percent of its annual 1.6 million ton output to overseas traders including Noble Group Ltd., Glencore International AG and Standard Bank Group Ltd.

Almost 13 million people have been left homeless by floods in eight states in the nation this monsoon season. Army and navy personnel were deployed in Orissa after rivers in the eastern state breached their banks and changed course last month, inundating villages.

Daily production of alumina dropped by half to about 2,200 tons for a 10-day period ended Aug. 4, following a 30 percent fall in aluminum output in June, the company earlier said. The company has imported at least 230,000 tons of coal since June to overcome the shortage.

National Aluminium requires 14,000 tons of coal daily to run its 960-megawatt power plant. Electricity accounts for 30 percent of costs for aluminum smelters.

The company makes 345,000 tons of the lightweight metal annually. Two tons of alumina produces a ton of the metal, used to make beverage cans, cars and airplanes.