Riviera Travel has become the latest operator to withdraw tours to Russia amid the escalating Ukraine conflict.
The company has joined many others in the trade responding to the Russian military invasion.
It came as the Foreign Office advised against all travel to Russia.
The Riviera Travel agency sales team tweeted that the firm had been closely monitoring the situation between Russia and Ukraine.
A spokesperson said: “We’re shocked and deeply saddened by the current situation in Ukraine.
“In light of these circumstances, we have taken the decision to cancel all of our tours and cruises to Russia for the foreseeable future.”
The company added on its website: “We will be contacting customers with existing bookings.
“Our team will be exceptionally busy over the next few days, and therefore it may take us up to two weeks.
“We will contact guests in departure date order and would be extremely grateful if you could wait for us to contact you. Please do bear with us, your patience is hugely appreciated.”
Viking Cruises earlier cancelled all 2022 Kyiv, Black Sea and Bucharest itineraries and said it was reviewing trips that include Russia.
Ocean cruise companies are amending Baltic itineraries to avoid calls into St Petersburg.