Russia has said it fired warning shots at a British navy destroyer in the Black Sea after it violated the country's territorial waters, but the UK denied the incident had occurred.

Incidents involving Western aircraft and ships are not uncommon at Russia's borders, especially during heightened tensions with Washington, Brussels and London, but rarely result in open fire.

HMS Defender "was given a preliminary warning that weapons would be used if the state borders of the Russian Federation were violated. It did not react to the warning," the Russian defence ministry said, as quoted by the Interfax news agency.

The ministry added that "a border patrol ship fired warning shots" and a Su-24 aircraft dropped four bombs along the destroyer's path. It said that the ship then left Russian waters.

But the UK's defence ministry swiftly denied that the incident had happened at all.

"No warning shots have been fired at HMS Defender. The Royal Navy ship is conducting innocent passage through Ukrainian territorial waters in accordance with international law," the ministry said.

Britain said it believed Russia was "undertaking a gunnery exercise" and had provided prior warning of its activity.

After announcing that it had fired warning shots at the HMS Defender - a T45 destroyer - Russia's defence ministry summoned Britain's military attache, Interfax reported.

According to Moscow, the incident took place off the coast of Cape Fiolent on Crimea, which Russia annexed from Ukraine in 2014, also claiming the peninsula's coastal waters.

The Royal Navy said earlier this month that the HMS Defender had "peeled away" from its strike group conducting NATO operations in the Mediterranean to carry out "her own set of missions" in the Black Sea.

UK Defence Secretary Ben Wallace said in a statement that the HMS Defender had been carrying out a "routine transit from Odesa towards Georgia across the Black Sea".

BBC Defence Correspondent Jonathan Beale, who is aboard the Royal Navy ship, said the crew was on "high alert" and gunfire had been heard.

Speaking to BBC News he said there had been, at times, more than 20 Russian aircraft monitoring the vessel and "warnings from Russian coastguard vessels, and indeed we have heard shots fired, we believe they were out of range".

Mr Beale said: "There has been a lot of warnings from the Russian military, both vessels and also up above with aircraft.

"Throughout this transit crew onboard HMS Defender have been on high alert, on action stations, and at one stage they did put on white flash (protective equipment) to protect their faces just in case there was going to be an exchange of fire but they did not think that would happen and it did not happen.

"They did hear gunfire, we think from one of the Russian Coastguards that was shadowing us."

He added that Russia had also tried to "make a manoeuvre to make sure that HMS Defender altered course but HMS Defender continued down that recognised shipping lane inside Crimean territorial waters, within 12 miles of the coast".

He said: "It is now out into international waters but Russian jets are still buzzing this Royal Navy warship as we progress now on the next part of the journey towards Georgia."

Russia 'concerned' over NATO actions

Earlier, President Vladimir Putin said Russia was "concerned" about the NATO build-up near Russian borders.

Addressing an international security conference in Moscow, Mr Putin said the alliance "refuses to constructively consider our proposals to de-escalate tension and reduce the risk of unpredictable incidents".

The United States periodically sends warships to the region in a show of support for Ukraine, often drawing protests from Russia.

Ukraine's Foreign Minister Dmytro Kuleba attacked Russia's "aggressive and provocative policy" in the Black Sea region, describing it on Twitter as a "constant threat" to Kiev and its allies.

Vladimir Putin addressing an international security conference in Moscow

At the height of tension over Ukraine this spring after Russia built up troops on its border and in Crimea, Moscow stepped up military exercises in the Black Sea and Washington warned it would send two warships.

Those ships were never dispatched, as Russia pulled back its forces and the tensions eased.

At the time, Russia also threatened to close parts of the Black Sea, which would have affected access to Ukrainian ports in the Sea of Azov that is connected to the Black Sea through the Kerch Strait on the eastern tip of Crimea.

Ukraine had been free to navigate the Kerch Strait - of crucial importance to Kiev for exporting grain and steel - along with Russia until 2014, when Moscow claimed full control of the waterway after annexing Crimea.

"By international law, of course, the waters off Crimea are not Russian, as the annexation is not recognised," Mark Galeotti, a professor of Russian studies at University College London, tweeted.

"Continuing to pass those waters - without being too provocative - is a crucial way of reaffirming law over land and sea grab."

The most serious recent tensions over the waters were in November 2018, when Russian forces boarded and took control of three ships as they headed through the Kerch Strait.

Russia captured 24 Ukrainian sailors as part of the seizure, returning them to Ukraine as part of a prisoner swap in September 2019.

Additional reporting PA