There will be no G8 summit in Russia this year, David Cameron said in a further sign of efforts to isolate Moscow over the Ukraine crisis.
The Prime Minister said it was "absolutely clear" the meeting could not go ahead.
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Speaking in The Hague ahead of a meeting of G7 leaders, he said: "We should be clear there's not going to be a G8 summit this year in Russia. That's absolutely clear."
Preparations for the planned June summit in Sochi had already been suspended as a result of Russia's actions in neighbouring Ukraine.
Mr Cameron, US President Barack Obama and other leaders of the group of the world's richest countries will consider Russia's future in the organisation amid ongoing fears about Moscow's military intentions in Ukraine.
The Prime Minister was joining his counterparts in a hastily-convened gathering of leaders of the G7 countries, the first such meeting to take place without Russia for more than a decade.
The G8 is made up of the G7 of the UK, US, Germany, France, Italy, Canada and Japan plus Russia.
Mr Cameron said: "We will be meeting tonight, the seven other countries of the G8, to determine the way forward.
"But frankly it's Russia that needs to change course."
The Prime Minister said reports of Russian troops massing on Ukraine's border were "concerning" and warned president Vladimir Putin that a fresh round of sanctions would follow if his forces marched any further into Ukrainian territory.
Concerns remain about Russia's military ambitions in Ukraine, following the annexation of Crimea, with Nato's supreme commander warning that Moscow had deployed a "very, very sizeable and very, very ready" force on the country's border.
US General Philip Breedlove raised the prospect that the Kremlin could even seek to take control of a Russian-speaking section of nearby Moldova.
Mr Cameron said: "These reports are concerning and we need to send a very clear message to the Russian government and to president Putin that it would be completely unacceptable to go further into Ukraine, and that would trigger sanctions from the EU, from the US, from other countries as well.
"We need to be very, very clear about that."