The leaders of the Group of Seven countries are to snub Russia over its invasion of Crimea by holding a summit in Brussels in June.
A meeting of the G8, which includes Russia, had been planned for the Winter Olympic resort of Sochi that month. But following the annexation of Crimea, the remaining G7 nations decided at a meeting last night in The Hague to carry on without Russia. They said there will be no further Russian involvement in the meetings until it changes course.
Prior to last night's announcement, David Cameron said the original meeting could not go ahead. The Prime Minister who is at the emergency talks in The Hague, said: "We should be clear there's not going to be a G8 summit this year in Russia. That's absolutely clear."
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Preparations for the June summit in Sochi had 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 fears about Moscow's intentions for Ukraine.
The Prime Minister was joining his counterparts in a hastily convened gathering of G7 leaders, the first such meeting to take place without Russia for more than a decade.
The G7 comprises the UK, the US, Germany, France, Italy, Canada and Japan. The group became the G8 after the addition of Russia.
Mr Cameron said the G7 leaders had met last night to determine a way forward, but added: "Frankly it's Russia that needs to change course."
Mr Cameron said reports of Russian troops massing on Ukraine's border were concerning and warned President Vladimir Putin a fresh round of sanctions would follow if his forces marched further into Ukrainian territory.
Nato's supreme commander warned 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: "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."
The Hague summit, which has been overshadowed by events in Ukraine, is aimed at ensuring nuclear material does not fall into the hands of terrorists.
Mr Cameron also held talks in The Hague with Danish Prime Minister Helle Thorning-Schmidt, whose husband, Stephen Kinnock, has been selected to fight a safe seat for Labour in next year's General Election. Ms Thorning-Schmidt took the "selfie" photograph posing with Mr Cameron and Mr Obama at the Nelson Mandela memorial in South Africa last year.
Number 10 said Mr Cameron and Ms Thorning-Schmidt discussed Ukraine, as well as the make-up of the next European Commission and the Prime Minister's EU competitiveness agenda.
Ukraine's fledgling government has ordered its troops to retreat from Crimea, ending days of wavering as Western leaders tried to present a unified response to Russia's increasing control of the peninsula. Russian forces have been seizing Ukrainian ships and military installations in Crimea, including a naval base near the eastern Crimean port of Feodosia.