LONDON -- British Royal Navy warship HMS St Albans returned to its base in Portsmouth Tuesday after spending Christmas Day escorting Russia's newest warship Admiral Gorshkov as it sailed through the North Sea close to British territorial waters.

The Ministry of Defense (MOD) in London said there has been an upsurge in Russian units transiting British waters during the current festive season.

In an official statement Tuesday the Royal Navy said the type 23 frigate was called upon to sail on Dec. 23 to keep watch on the Admiral Gorshkov.

"HMS St Albans remained at sea on Christmas Day to monitor the Russian frigate, keeping track of its activity in areas of national interest."

"The Royal Navy frigate will return to Portsmouth today (Boxing Day) and remain ready for very short notice tasking over the holiday period," said the statement.

The Royal Navy's HMS Tyne was called to escort a different vessel, a Russian intelligence-gathering ship, through the North Sea and the English Channel on Christmas Eve (Dec. 24), said the MOD.

A Royal Navy Wildcat helicopter from 815 Naval Air Squadron, based at Yeovilton, was dispatched over the period to monitor two further Russian ships.

So far, there is no comment from the Russian side.

Currently more than 4,000 Royal Navy sailors and Royal Marines are deployed across the globe or on heightened readiness to respond to anything that may come their way.

A total of 1,540 men and women are deployed from the sands of the Gulf to the depths of the Atlantic, helping to safeguard the UK's economic interests and maintain security at sea, said the Royal Navy. A further 2,485 are being held at immediate readiness for any defense or civil task that may emerge over the current festive period.