NEW DELHI (Reuters) - An Indian state said in October that Mercedes-Benz improved wastewater and air pollution management at its only car factory in the country after officials detected environment law lapses in recent inspections, government documents show.

Pollution control officials in the western state of Maharashtra signed off on Mercedes' compliance with environment norms in an Oct. 11 visit report, reviewed by Reuters.

The clearance is a relief for the German carmaker, India's top luxury car seller, which announced plans in January to launch over a dozen models and invest $24 million in the country this year.

In August, state officials made surprise checks at the Mercedes plant in Chakan, Maharashtra, and found the company was discharging untreated effluent and emissions, "causing water and air pollution into the environment," according to a government notice sent to Mercedes on Sept. 19, which Reuters has reviewed.

The notice recorded a total of nine non-compliances by the German carmaker, including inadequate maintenance of its sewage treatment plant, the presence of pollution causing compounds near its paint booth and failure to install some required emission control devices.

The accusations triggered a political storm in India's richest state as opposition lawmakers said it could damage the region's reputation as a major hub for foreign companies.

Industrial pollution is a major concern in India, and Prime Minister Narendra Modi and state governments have set stringent targets to limit air and water pollution caused by factories and vehicles.

However, Mercedes said there were no "non-compliances at our plant as alleged" and it was not harming the environment, according to a private letter to pollution control officials dated Sept. 26, which Reuters has seen.

Mercedes' response to the state government and details of the Oct. 11 visit by inspectors have not been reported previously.

The company did not respond to requests for comment on Indian officials noting improvements at its plant. But it said in a statement to Reuters this week that it continues to cooperate with officials and had addressed all queries raised.

The state government did not respond to Reuters queries.

The government documents said when the plant was inspected again in October, officials noted the company had improved its management of wastewater treatment plants and no air pollutants were found being generated during painting.

"Operation & maintenance of ETP (Effluent Treatment Plant) found improved...maintenance of plant and machinery is carried out," the officials noted in the report.

The Mercedes plant is located 140 km (87 miles) from India's financial capital Mumbai and is close to factories of other automakers like Volkswagen and Mahindra & Mahindra. Last year, Mercedes sold a record 17,400 cars in India, beating BMW to second spot.

(Additional reporting by Aditi Shah; Editing by Aditya Kalra and Raju Gopalakrishnan)

By Arpan Chaturvedi