NEW DELHI (Reuters) - Indian mobile operators added a record 15.64 million customers in March, helped by the expansion of networks to smaller towns and rural areas, data from the telecoms regulator showed.

The mobile subscriber base in the world’s fastest-growing wireless market rose by 50 percent, or more than 130 million, to 391.8 million in the 12 months ended March, the Telecom Regulatory Authority of India said.

India is the second-biggest market for wireless services, lagging only China which has more than 600 million users.

Indian operators had added 15.41 million customers in January and 13.45 million users in February.

The country also had about 38 million fixed-line subscribers at end-March.