Britain stands in "full support" of the Czech Republic after Prague accused Moscow of involvement in an ammunition depot explosion, UK Foreign Minister Dominic Raab said.
Czech police on Saturday said they were searching for two men in connection with serious criminal activity, carrying Russian passports in the names of Alexander Petrov and Ruslan Boshirov.
They said the men were in the country in days leading up to the blast at the Czech depot in 2014.
Those were the aliases used by two Russian military intelligence, or GRU, officers who British prosecutors charged with the poisoning of former Russian spy Sergei Skripal and his daughter Yulia with the nerve agent Novichok in 2018.
Moscow denied involvement in that incident.
"The UK stands in full support of our Czech allies, who have exposed the lengths that the GRU will go to in their attempts to conduct dangerous and malign operations, and highlights a disturbing pattern of behaviour following the attack in Salisbury," Mr Raab said on Twitter.
Ties between Britain and Russia have plunged to post-Cold War lows, with London calling Moscow "the most acute threat to our security" in the Euro-Atlantic region.
The government made the statement in its foreign and defence policy statement last month.
On Friday, Russian ambassador to the UK Andrei Kelin told the BBC he had not seen Mr Raab for more than a year.
"In the recent year our relations have become worse, even worse," Mr Kelin said.