British foreign minister David Cameron said he opposes sending Western troops to Ukraine, even for training missions, in an interview with German daily Sueddeutsche Zeitung published on Saturday.
Cameron said training missions are best carried out abroad, noting that Britain has trained 60,000 Ukrainian soldiers that way.
Placing foreign soldiers in Ukraine would provide targets for Russia, he said.
French President Emmanuel Macron set off a stir among his allies on February 26 when he did not exclude sending Western troops to Ukraine to help it fend off Russia's invasion.
Britain later confirmed that it had sent small units to Ukraine to help with medical training, but a spokesperson for Prime Minister Rishi Sunak said the country does not foresee large-scale deployments.
On Friday, French Defence Minister Sebastien Lecornu said there were no plans for the moment to send combat troops, but that Ukraine's allies could consider specific training or de-mining missions.
In his interview with Sueddeutsche Zeitung, Cameron said Ukraine needed more long-range weapons and that he was willing to work with Berlin to lift its reticence to supplying German-made Taurus cruise missiles.
Cameron wouldn't directly address suggestions that Berlin provide Britain with Taurus missiles to free up the UK to send more British-French Storm Shadow cruise missiles to Ukraine.
Berlin has refused to deliver Taurus missiles to Ukraine, fearful that its 500-kilometre (310-mile) range would be used to hit targets deep into Russian territory.
Since last May, France and Britain have supplied Ukraine with Storm Shadows -- called Scalp in French and with a 250-kilometre range -- while the United States has sent ATACMS, which have a range of 165 kilometres.