Boris Johnson has insisted Royal Navy warship HMS Defender was sailing legally in Ukrainian waters and that Russia did not any fire warning shots.
Russia has accused the UK of “barefaced lies” over Wednesday’s incident and said it would respond robustly to any future incursions into what it says are Russian waters.
It summoned the British ambassador in Moscow for a dressing down, while a Kremlin spokesman called it a “deliberate and premeditated provocation”.
“In the event of a repeat of unacceptable provocative action – if those actions go too far, no options can be ruled out in terms of legally defending Russia’s borders,” added Dmitry Peskov.
The UK rejects Russia’s claim that a border patrol boat fired warning shots and that warplanes dropped bombs into path of the ship off the Crimean coast.
Speaking on Thursday, Boris Johnson said it was “not my information” when asked if the Russians had fired warning shots.
“My understanding is that the Carrier Strike Group proceeded in a way you would expect through international waters and in accordance with the law,” said the prime minister.
He added: “We don’t recognise the Russian annexation of Crimea – it was illegal. These are Ukrainian waters and it was entirely right to use them to get from A to B.”
Foreign Secretary Dominic Raab has also said shots were not fired and called the Russian account “predictably inaccurate”.
The Ministry of Defence said it had been made aware in advance that the Russians were conducting “gunnery exercises” in the area.
“No shots were directed at HMS Defender and we do not recognise the claim that bombs were dropped in her path,” it said.
However, a BBC journalist on board the 152 metre-long ship said Russian planes had flown nearby and he also heard radio warnings that shots would be fired if HMS Defender didn’t change course .
He said firing was later heard but “well out of range”.
Foreign ministry spokeswoman Maria Zakharova accused Britain of “barefaced lies” over the incident.
Russia claims the British ship had gone as far as three kilometres (2 miles) into Russian waters near Cape Fiolent, near the port of Sevastopol in Crimea.
Crimea was seized from Ukraine in 2014 by the Russians, who claim ownership of waters around its coast.
Western countries regard Crimea to have been taken illegally.
Mr Johnson also rejected the assertion that the relationship with Russia was now at a new low, following other recent incidents such as the poisoning of former spy Sergei Skripal in the UK in 2018.
“I can remember times in my own lifetime when things have been far worse,” the prime minister said.
Sky’s Moscow correspondent Diana Magnay said the incident was to a large extent about “testing each other’s mettle” and seeing “how far Russia is prepared to go to defend what it claims are its territorial waters – and how far the UK and NATO are prepared to go to defend Ukrainian sovereignty”.