The Royal Navy said it would closely monitor a Russian navy fleet travelling through the North Sea and appearing to head towards the English Channel.
According to Sky News, the Royal Navy said it would “man-mark every step of the way” the group.
The vessels are expected to pass through the Dover Straits on Friday morning, the Sun reported.
The Russian fleet, which includes the aircraft carrier Admiral Kuznetsov, is believed to be on its way to Syria, according to the Independent.
Type 45 destroyer HMS Duncan sailed from Portsmouth to monitor the group.
HMS Richmond has already escorted it from the Norwegian Sea towards the North Sea, Sky News reported.
The Guardian reported that the Navy said it appeared the flotilla would pass through the Channel, although quoted a spokesman as saying it was “hard to say when”.
A Royal Navy spokesperson said: “UK and Nato assets routinely monitor warships from other nations when they enter our area of interest and this will be no different.”
Nato said that the move did not “inspire confidence” that Russia was pursuing a political solution to the crisis in Syria.
The Daily Mail quoted a Nato official as saying: “Russia has the right to operate in international waters.
“There are plans in place for Nato navies to monitor the Russian ships as they head for the Mediterranean.
“At the same time, the deployment of the carrier group to the eastern Mediterranean does not inspire confidence that Russia is working towards a political solution to the conflict in Syria.”
However, Reuters reported that a senior Nato diplomat, speaking on condition of anonymity, said: “They are deploying all of the Northern fleet and much of the Baltic fleet in the largest surface deployment since the end of the Cold War.”
“This is not a friendly port call. In two weeks, we will see a crescendo of air attacks on Aleppo as part of Russia’s strategy to declare victory there.”
Russia, which supports Syrian President Bashar al-Assad with an air campaign against the Western rebels in the devastated eastern part of Aleppo, has said the deployment will target Islamic State militants in Syria.
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