Gordon Brown has threatened a "root and branch" review of relations with Russia, insisting it must not be allowed to hold the West to ransom. The Prime Minister accused the Kremlin of "dangerous and unacceptable" behaviour, saying it was using energy resources as a "policy tool". EU leaders will meet in Brussels on Monday to discuss the South Ossetia crisis, and Mr Brown said he had warned Russian president Dmitry Medvedev to expect a "determined" response. The summit comes amid growing fears that Moscow could "turn off the taps" in order to win any showdown, potentially wreaking havoc on Western economies. The PM has argued that in the longer term the world would need to reduce its reliance on Russia for energy, by seeking out alternative suppliers and pushing ahead with other sources such as nuclear power. He insisted: "My message to Russia is simple. If you want to be welcome at the top table of organisations such as the G8, OECD and WTO, you must accept that with rights come responsibilities." He said: "We want Russia to be a good partner in the G8 and other organisations, but it cannot pick and choose which rules to adhere to. "That is why I will argue that Russia should accept Georgia's territorial integrity and international mechanisms for addressing these conflicts, and withdraw troops to their previous positions. "And, in the light of Russian actions, the EU should review - root and branch - our relationship with Russia. "We should continue to strengthen the transatlantic relationship and may need to meet more regularly as the G7. Mr Brown highlighted the fact that Britain is set to import two-thirds of its gas and almost half its oil by 2020, as prices for the resources soar. He insisted that the EU could not risk sleepwalking into an energy dependence on less stable or reliable partners, especially when states such as Russia were "increasingly using their energy resources as policy tools".