Meanwhile, as Geological Survey of India ship Samudra Ratnakar found some leads at a depth of around 3,000 meters, officials said it was not clear if it was the debris of the aircraft.
"The ship has tracked some echoes from the seabed but it will be a long process to verify if there is any debris belonging to the AN-32," IAF spokesperson Wing Commander Anupam Banerjee told IANS.
According to the Geological Survey of India, the Samudra Ratnakar, which was part of the search operation, had detected some linear pieces.
A GSI official told IANS that the objects, around 200 to 300 nautical miles from Chennai, could even be rocks on the sea bed.
Indian Navy Spokesperson Captain D.K. Sharma said: "The search for AN-32 is in progress in right earnest."
Sharma added that there were no concrete leads.
A month on, the search is being carried on with two Indian Navy and one Coast Guard ship for scanning the surface of the sea.
National Institute of Ocean Technology's vessel, Sagar Nidhi, and Samudra Ratnakar are carrying on the sub-surface search while aerial survey is being carried out by surveillance aircraft P8I , transport aircraft C130J Super Hercules and Coast Guard's Dorniers.
The plane with 29 people on board went missing shortly after taking off from Chennai for Port Blair on July 22.
The recorded transcript of air traffic radar showed the last pick up of the aircraft was 151 nautical miles east of Chennai when it took a left turn with rapid loss of height from 23,000 feet.
A flotilla of Naval and Coast Guard ships and aircraft were deployed on the search operations hours after the aircraft went off radar.
Data from Indian satellites was scanned and help was also sought from other countries to locate the missing aircraft.
Defence Minister Manohar Parrikar, in a detailed statement made in parliament, also clarified that the aircraft, an upgraded version of IAF's workhorse, had "adequate lifetime" and had undergone just one overhaul.
