Chennai/New Delhi: Search for the missing AN-32 Indian Air Force plane continued for the fifth day on Tuesday, with Defence Minister Manohar Parrikar saying that around four-five search leads had turned out to be "bad". The AN-32 which went missing on July 22 with 29 people on board remains untraced despite massive search operations in the Bay of Bengal, the authorities said on Tuesday. Parrikar told reporters that the agencies are trying to concentrate on some links or sound emitting from some area in the sea. He also discounted reports of the airworthiness of the AN-32, saying it is one of "the safest aircraft the IAF flies". Speaking of the rescue efforts, Parrikar told reporters: "A lot of resources are in place for the search and rescue operations for the missing Indian Air Force, AN-32 aircraft, but all leads till now have turned out to be bad. We are trying to concentrate on some links or sound which have been emitted from some area." A state-of-the-art ice-class research vessel, Sagar Nidhi, of the National Institute of Ocean Technology has been called from Mauritius for the search operation. Sagar Nidhi comes with Dynamic Positioning System to keep its position stable, which is required for oceanographic research. Parrikar also contradicted Coast Guard official who said the ELT (Emergency Locator Transmitter) did not work in a Dornier plane of the Coast Guard that had crashed last year. "I think the submarine finally located the Dornier with the same beeps. Initially sound might not have come due to the depth of water, but when the submarine went in there they identified the location," he said. The Minister added that no beeps from the missing AN-32 have been heard so far. "...Can't say whether it is operating or not now but we have not been able to hear it," he said. The Defence Minister also spoke in the Rajya Sabha on the issue during Question Hour. "There are small leads. There were 4-5 blinks which were noticed, we are trying to find out whether they are misleading... We have used satellite imagery. The P8I aircraft is being used extensively, almost 30 ships including of the Coast Guard and the navy, and merchant ships are there. A submarine is also in the area," he said. "We are getting a deep sea rescue vessel also." Asked about reports of technical glitches in the missing AN-32, the Minister said: "I will not like to comment on that but I can say very clearly that this (AN-32) is one of the safest aircraft the IAF flies. "There have been only two reported accidents in the last 10 years. What you are talking of are small minor issues that crop up every time you fly and they are rectified," he said. Coast Guard officials meanwhile told IANS that there is no trace of the missing aircraft so far. The Navy, Coast Guard and IAF are searching for the plane or its debris. The plane with 29 people on board went missing shortly after taking off from Chennai for Port Blair. The Indian Space Research Organisation (ISRO) is using its Radar Imaging Satellite to detect any floating debris. The IAF has not divulged the names of the 29 passengers. Asked about the nature of the cargo on board the aircraft, IAF spokesperson Anupam Banerjee declined to comment. "It is not possible to share such information," Banerjee told IANS. 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.