Indian Navy chief Admiral Karambir Singh said on Tuesday said that the presence of Chinese ships in the Indian Ocean is increasing and warned that ships operating in "our Exclusive Economic Zone have to take clearance."

Admiral Singh was commenting on the recent incident when the Indian Navy drove away a suspicious Chinese vessel operating in the Indian waters near Port Blair.

"Our stand is that if you have to work in our Exclusive Economic Zone, then you have to take our clearance," he said.

Noting that the presence of Chinese ships in the Indian Ocean is increasing, he assured that the naval forces have been keeping a close watch on them and are fully prepared to deal with national security challenges.

His remarks came ahead of a scheduled joint naval exercise of China and Pakistan in the North Arabian Sea.

Speaking at the annual press conference in Delhi, held a day ahead of the Navy Day, he said the Chinese vessel must have entered the Indian Ocean Region to take part in the exercise.

As per the government sources, the suspicious Chinese vessel was carrying out research in the Indian waters near Port Blair in Andaman and Nicobar Islands. The Chinese research vessel Shi Yan 1 was detected by maritime surveillance aircraft.

After it was discovered that a Chinese vessel was present and carrying out research in the Indian Exclusive Economic Zone, the Indian Navy sent a warship to monitor its activities.

The chief of naval staff also expressed his concern over the decline in Navy's share in defence budget from 18% in 2012 to 12% in 2018.

Speaking on future acquisition plans of the Navy, Singh said the force plans to have three aircraft carriers in the fleet in the long term.

"As the Navy chief, I am convinced that the country needs three aircraft carriers so that two are operational at all times. We think, it should be 65,000 tonnes with electromagnetic propulsion," he was quoted as saying by ANI.

We should have the first indigenous aircraft carrier IAC-1 fully operational by the year 2022 and it will operate with the MiG-29K, he added.

"50 warships and submarines of the Indian Navy are under construction of which 48 are on order in Indian shipyards," he further said.

Singh added that the Letter of Acceptance (LoA) from the US for 24 MH-60R multi-role helicopters is here and the deal is expected to be signed.

On Navy's plan to include Light Combat Aircraft (LCA) in its fleet of aircraft, he said, "Navy was the first to support LCA... Defence Research & Development Organisation (DRDO) now wants to give us twin-engine deck-based aircraft and if it meets our timelines and requirements, we will take it."

Commenting on the creation of the post of Chief of Defence Staff, he said, "My expectation is that the Chief of Defence Staff (CDS) is suitably empowered to carry out all the decisions. Prime Minister has taken a historic decision. Navy had presented all its points on the issue to the government."