Within weeks of an increase in mobile tariffs by some of the major players, the telecom regulator has asked them to justify the increase in call rates.

In a recent communication to the operators, including Bharti Airtel, Vodafone Essar and Idea Cellular, the Telecom Regulatory Authority of India has asked whether they have increased their prices and sought the details of the increased tariff plans. Mobile tariffs are currently under forbearance, which means these are determined by market forces.

However, Trai can intervene to protect the consumers and operators interest. A senior executive from one of the telecom companies mentioned above confirmed receiving the communication from Trai.

Trai Chairman J S Sarma could not be reached for comments. When contacted, Cellular Operators Association of India Director General Rajan Mathews also confirmed that Trai had sought the details of the increased tariff plans from the operators.

"There has been no hike in the tariff in this industry for last one or two years. With the overall increase in operating cost of service providers, they are not left with much of a choice but to increase tariffs.

"However, the increase is not major. We still have the cheapest tariffs and it won't impact the usage of the consumers," Mathews said.

Currently, operators are required to notify Trai for any change in tariff plans, introduction of new plans as well the changes in call rates within 30 days.

Early in the year also, Trai had sought details from the operators when the tariffs hit a low to just one paisa per second, amid allegations that new telecom operators were resorting to predatory tariffs.

Bharti, Vodafone Essar and Idea Cellular had recently increased the prepaid tariffs in select circles by as much as 20 per cent.

Bharti was the second private telecom operator to increase tariffs after Tata Docomo, which raised the prices in one or two circles about two months ago.

Subsequently, Vodafone Essar and Idea Cellular also increased the prices in some circles.