UFO investigator Philip Mantle uncovered former top-secret files from the Kremlin in his book Russia's USO Secrets: Unidentified Submersible Objects in Russian and International Waters

Russian submarines are fighting a secret war with aliens deep under the oceans, according to startling new claims.

British investigator Philip Mantle has revealed former top-secret files from the Kremlin in his book Russia's USO Secrets: Unidentified Submersible Objects in Russian and International Waters

It's claimed Soviet subs are playing a game of cat and mouse with strange underwater craft.

Former veterans are now speaking out about their close encounters - including hostile acts - at sea during the Cold War.

In scenes straight out of Hollywood blockbuster Battleship, they have described how UFOs would appear in the sky before diving down beneath the waves.

Philip, 62, of Pontefract, West Yorks, - who co-wrote the book with Paul Stonehill - said: "The USO phenomena looks set to be the future of UFO research in general.

(Image: Trangle News)

"More and more researchers around the world are taking a closer look at the USO subject.

"It is strongly suggested that both Russian and American subs have encountered USO's in various parts of the world.

"We know more about the surface of the Moon than we do about our oceans here on Earth."

In one terrifying incident, a captain ordered depth charges to be dropped into the path of a USO which changed direction and sped off.

Author Philip Mantle says Russian submarines are fighting a secret war with aliens deep under the oceans (Image: Trangle News)

Lieutenant-Commander Oleg Sokolov told students that while on duty he spotted a strange object through a periscope rising out of the water.

Another crew watched as a cigar shaped UFO shot three beams of light down into the Atlantic Ocean.

The UFO was about 200-250 metres long and slowly descended into the ocean making a strange hissing sound about half a mile from the submarine.

Picture taken by Semyon Tegyov in Kazakstan on 27th April 1995 (Image: Trangle News)

But the object was not tracked on radar.

Marine scientists in the port city of Sevastopol, Ukraine, claim they spotted a huge "wheel" rotating below the Black Sea while they were deep sea diving.

In 1951, a Soviet submarine encountered a gigantic underwater object heading towards the shores.

The captain ordered depth bombs to be dropped into the path of the USO.

Illustration from SETKA file - KGB chairman Abdropov who was interested in the case (Image: Trangle News)

The object did not react to the attack and stayed on its course before darting towards the surface.

At the depth of 50 meters it stopped its ascent, changed course and departed.

Russian seaman again observed a UFO in the Mediterranean in July 1978, according to the files which were translated by Ukranian-born Stonehill.

KGB Sham’s letter accompanying released 124 pages of the document (Image: Trangle News)

The captain of Soviet motor ship Yargora immediately sent a radiogram to the Soviet Academy of Sciences in Moscow. The object was shaped like a flattened-out sphere and was a white pearl colour.

Other UFOs have reportedly appeared over Soviet submarine bases forcing the Soviet General Staff to take them seriously.

A study by the Anomalous Phenomena Commission of the Russian Geographical Society in Saint Petersburg concluded UFOs were real.

Russia's USO Secrets is published by Flying Disk Press.