"Uninterrupted search by Coast Guard and Naval ships and aircraft continues for the fourth consecutive day," a defence ministry statement said.
"INS Sandhayak arrived in the area of search in intervening night of June 11/12 and has commenced the search (along the coastline Cuddalore-Karaikal)," it said.
"The vessel is using its underwater detection equipment to detect any transmission from the Sonar Locator Beacon of the aircraft.
"Aerial search by Paramotors (motorised steerable parachutes attached to paratrooper's back) through Coastal Security Group of Tamil Nadu was undertaken 30 km south of Cuddalore on Thursday along the coast over marshy mangroves, which is not approachable by sea," the statement said.
INS Sindhudhvaj, a submarine of the Indian Navy, is expected to join the search by Saturday.
The CG Dornier aircraft went off the radar at 9.23 pm on Monday during a routine surveillance mission along the state coast and Palk Bay after it took off from the Chennai station.
"Assistance of the National Remote Sensing Agency has also been sought for analysis of the satellite imagery of the area, for possible location of the aircraft," it said.
The defence ministry also said the Indian National Centre for Ocean Information Services, Hyderabad, has been requested to undertake 'SAR model programming' for the missing aircraft and to identify the most probable area.
National Institute of Ocean Technology here has been approached for oceanographic analyses of the area and feasibility of deploying their research vessel 'Sagar Nidhi' for augmenting the sub-surface search.
Also, a team from Omcar Foundation, Thanjavur, has embarked onboard 'ICGS Sarang' for undertaking underwater photography and acoustic survey.
"Unrelenting efforts by Coast Guard and Naval ships/ aircraft to locate the missing Dornier and crew continues. Interaction is also being maintained with the family members of the air crew, and are being apprised on the progress of the search operation," the ministry said.