Norway said that up to 5,000 NATO troops would take part in anti-submarine warfare exercises off its coast in early May, amid growing regional tension over alleged submarine sightings.

The exercise, named ‘Dynamic Mongoose,’ will take place from May 4 to 13 in the North Sea and Skagerrak and will involve a number of submarines, surface ships and aircraft, according to a statement posted on the Norwegian Armed Forces official website.

Finland, which is not a member of NATO, said on Tuesday that its navy had fired warning shots at a possible submarine in the waters off Helsinki.

In October, armed forces in Sweden, also not a NATO member, hunted unsuccessfully for a week for what they believed to be a foreign submarine in waters close to Stockholm.

According to a statement on their website, NATO will practice anti-submarine warfare in the air, on the surface and underwater. The Flag Commander points out that it is difficult to find submarines along the Norwegian coast. He, therefore, believes the exercise is a good place to get better at such operations.

"Norway is an attractive place to train and practice for foreign forces," Commodore Ole Morten Sandquist, chief of the Norwegian Navys combat force, was quoted as saying. "It is important for Norway that NATO is good for anti-submarine operations in our region," media reports.