Vladimir Putin is behaving like a "mid 20th-century tyrant" over Ukraine and leading Russia in a way "civilisation nations" shouldn't behave, Foreign Secretary Philip Hammond has warned.
Hammond also said supplying arms to Ukraine was not the right thing to do "at the moment", but added the UK's position would be kept under review if the situation on the ground changes.
Speaking on Sky News' Murnaghan programme, he said: "This man has sent troops across an international border and occupied another country's territory in the 21st century acting like some mid-20th century tyrant.
"We do not behave like that. Civilised nations do not behave like that in the 21st century. We live in a rules-based society. We want the Russian people to be part of that international community.
"We want Russia to enjoy the kind of economic growth and rising standards of living that people in the rest of Europe enjoy and we do not see any reason to tolerate this kind of outrageous and outdated behaviour from the Kremlin."
Hammond insisted there had to be a political solution to the crisis in eastern Ukraine and stressed that the proposed deal was "one of the last opportunities Russia will have" to avoid further damage to its economy.
He dismissed French President Francois Hollande's remark that this is the last chance for peace as "apocalyptic language", arguing there was already a "conflict situation" on the ground.
But Hammond added: "This is one of the last opportunities that Russia will have to avoid yet further significant damage to its economy which is bound to happen if the intransigence of Vladimir Putin forces the rest of the world to increase and tighten the sanctions from which Russia's economy is already reeling."
Germany has ruled out providing lethal aid to the Ukrainian forces in contrast to the US which is considering supplying arms in certain circumstances.
Hammond said Britain's position was currently not to provide arms to Ukraine, adding: "This is a national decision for each country to make.
"There is no military solution to this conflict. The Ukrainians can't beat the Russian army. That is not a practical proposition. There has to be a political solution and the Kremlin, Mr Putin, has to understand he will pay a political and economic price for what he is doing in the Ukraine.
"Britain's position is that at the moment we don't think supplying arms is the right thing to do but obviously if the situation on the ground changes we will keep that position under review."
He refused to be drawn on the circumstances under which the UK might consider supplying arms saying he would not talk about a hypothetical situation.
Hammond also said he believes the sanctions currently in place against Russia - combined with the falling oil price - are having the desired effect despite Putin's public reassurances that all is well.
He said: "Putin is toughing this out in his public presentation. You would expect him to do that. It's the kind of person he is.
"But we all know and Russians certainly know, thinking back to the days of the Soviet Union, that in the end the economic facts cannot be ignored.
"If your economy is cratering you cannot support the kind of foreign adventures Putin is undertaking, you cannot support the kind of security state structure that he has generated and that he needs to keep him there.
"So he will have to trim his behaviour to reflect the decline in the Russian economy and sanctions are a critical part of the pressure on him to change his behaviour."
The current negotiations are not about the annexation of Crimea, which Mr Hammond denounced as illegal, but he insisted Russia's withdrawal from it would be the next demand if the plan for eastern Ukraine is accepted by Putin.
He added: "Don't make it sound like that is an outrageous thing for us to demand."