Surveys are also underway in these states to detect gold deposits, the government has said.It said explorations in the three states had resulted in discovery of 41 kiberlites and 13 lamproite pipes, which are indicative of possible diamond deposits underneath.

Kimberlite and lamproite are solidified volcanic magma and work as elevators to bring diamonds with other minerals to the earth's surface.

"So far, a total of 339 Reconnaissance Permits (RPs) have been issued covering an areas of 4,66,556 sq km, out of which aerial surveys have been conducted in 27 RPs," an official statement by the Mines Ministry said.

It said kimberlite and Lamproites were discovered in Kalahandi, Nawarangpur, Nuapada and Bolangir districts of Orissa and in Kurnool, Prakasam and Anantapur districts in Andhra Pradesh. Explorations by CRA Exploration India Pvt Ltd in the state indicated discovery of several mineralised zones in Anantapur and Kurnool districts.

In Karnataka, these were discovered in Gulbarga district. The ministry said exploration permits had been given to several companies.