The Rostov-on-Don sub, described by Russia as the "quietest in the world", has appeared in the eastern Mediterranean Sea near Cyprus.

Dubbed the 'Black Hole' by Nato because of its ability to move around undetected, the submarine is equipped with missiles similar to those used by the warships of Russia's Caspian flotilla to strike ISIS targets.

The same vessel was reportedly used to bomb ISIS in their Raqqa headquarters in November.

Russia also struck the terror group in Syria with Kalibr cruise missiles from warships in the Caspian Sea in October.

The diesel-electric stealth sub is armed with 533mm torpedoes and water-to-surface cruise missiles, and its relatively small size helps it manoeuvre in shallow waters.

The 4,000 tonne sub, which can remain at sea for 45 days, has a top underwater speed of 20 knots (37kmph) and can dive to a depth of 300 metres.

It comes a day after Russia stoked tensions with Turkey when it sailed a warship carrying soldiers holding rocket launchers through its waters.

The Caesar Kunikov was photographed sailing through the Bosphorus strait on Sunday in what Turkey Foreign Minister Mevlut Cavusoglu described as "provocation".

Russia has been accused of creating an "arc of steel" from the Arctic via the Baltic region to Syria in a direct challenge to Nato's supremacy in the region. Express reported.

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