Kolkata: Earlier this week, an unwelcome guest came calling at the Andaman and Nicobar Islands, or near it, to put it correctly.

A blip appeared on the coastal radar screen on Tuesday sending alarm bells ringing in the islands, the Times of India reported on Saturday.

It was found upon subsequent surveillance that the vessel was a submarine tender of the People's Liberation Army Navy (PLAN) – a supply and support ship.

This led to the speculation among Indian Navy officials that one or more PLAN submarines could be present in the Area of Responsibility (AoR) of the Andaman and Nicobar Command (ANC).

As per the daily, Vice Admiral PK Chatterjee, commander-in-chief, ANC (CINCAN), said that it was not the first time that a Chinese ship had been detected around the island chains.

“In fact, there is greater focus on defences of the Andaman and Nicobar Islands as the situation has changed. There is frequent movement of certain navies in the AoR of ANC. There are both surface and sub-surface vessels. This is all the more reason why we should tighten our belts," Vice Admiral Chatterjee said, as per the newspaper.

The Andaman and Nicobar Islands are located some 1,200 kilometres from the mainland.

It is routine for the Chinese ships and submarines to be within a 500 km radius of the islands, which makes them vulnerable.