KIEV - Ukraine accused Russia on Monday of pouring more troops into Crimea as world leaders grappled with Europe’s worst standoff since the Cold War and the Moscow market plunged on fears of an all-out conflict.Russian Foreign Minister Sergei Lavrov said forces were needed in the flashpoint Black Sea peninsula until “the stabilisation of the situation” in the ex-Soviet nation and slammed Washington’s “unacceptable threats” against Moscow.Crimea - the strategic host to tsarist and Kremlin navies since the 18th century - has been under de facto occupation by Moscow-backed forces since President Vladimir Putin won parliament’s authorisation on Saturday to send troops into Ukraine. The price of oil surged over fears of a conflict while the Moscow market lost more than 12 percent on a Black Monday of trading that saw the ruble establish historic lows. British Foreign Secretary William Hague warned Russia of “consequences and costs” as he met Ukraine’s Western-backed but untested interim leaders in Kiev.The world’s richest nations have already threatened to strip Moscow of its coveted seat at the Group of Eight for menacing its ex-Soviet neighbour. But Europe and Washington appear to have limited options in dealing with Putin - a veteran strongman with mass domestic appeal who has cracked down on political freedoms and appears more interested in rebuilding vestiges of the Soviet Union than repairing relations with the West.Ukraine has soared to the top of the global agenda even as the brutal conflict in Syria rages and talks on Iran’s nuclear drive enter their most sensitive stage.“This cannot be a way in the 21st century to conduct international affairs,” Hague told reporters. “It is not an acceptable way to behave and there will be consequences and costs.” The crisis on the eastern edge of Europe threatens to blow up into the biggest test to global diplomacy since the fall of the Berlin Wall.It first erupted in November when protests began against the pro-Kremlin regime over its scrapping of an EU pact and culminated in a week of carnage last month that claimed nearly 100 lives and saw the downfall of president Viktor Yanukovych - now living in exile in Russia. “There was the (1962) Cuban missile crisis and the Soviet Union’s decision to send tanks into Prague (in 1968). But in that era, we were effectively in a state of war,” said Alexei Malashenko of the Carnegie Moscow Centre.Germany offered a rare glimmer of hope by announcing that Putin had agreed in telephone talks with Chancellor Angela Merkel Sunday to set up a contact group on Ukraine. Western allies in NATO also said they wanted to send international observers to Ukraine while engaging Moscow in direct talks. Washington added it would like to see a mission from the Organisation for Security and Cooperation in Europe (OSCE) deployed in the nation of 46 million “immediately”. Russia offered no immediate response to any of the proposals - all backed by interim leaders in Kiev who are trying to pull Ukraine closer to the European Union after replacing the Yanukovych regime.Lavrov said Kiev’s new leaders “intend to make use of the fruits of their victory to attack human rights and fundamental freedoms of minorities.”The UN Security Council will meet Saturday for a second round of emergency consultations, officials said, after Russia’s parliament approved the deployment of troops to Ukraine. The president of the Security Council, currently Luxembourg, invited members to “informal consultations” at 1900 GMT, a statement said. The announcement came just hours after Russian leader Vladimir Putin won approval from lawmakers to send Russian troops into Ukrainian territory. Britain’s ambassador, Mark Lyall Grant, tweeted that the meeting was called at London’s request. The UN envoy to Ukraine, Robert Serry, announced earlier that he was leaving the country because it was impossible to visit Crimea as requested by Secretary General Ban Ki-moon. Ban ordered Serry to visit the Crimea in a bid to de-escalate tensions after an emergency meeting of the UN Security Council on Friday.Crimea is now almost under complete control of Russian forces and local pro-Moscow militia who patrol both government buildings and the perimeters of Ukrainian barracks on the rugged Black Sea peninsula. “All military bases in Crimea are blocked,” regional defence ministry spokesman Stanislav Seleznyov told AFP. “All of the bases in Crimea are still under Ukrainian control. But they are surrounded,” the Ukranian defence official said.US Secretary of State John Kerry also warned ahead of his arrival in Kiev on Tuesday that Moscow risked losing its G8 seat over its “brazen act of aggression” in Ukraine.Russia’s foreign ministry said Monday that warnings by United States Secretary of State John Kerry over Russian military intervention in Ukraine were “unacceptable” threats. “We consider the threats against Russia made in a series of public statements by US Secretary of State John Kerry over the latest events in Ukraine and in Crimea to be unacceptable,” the Russian foreign ministry said in a statement on its website.Meanwhile, , a draft document showed Monday that Russia must change course on Ukraine and return its troops to their bases in Crimea or it risks a series of EU punitive measures, including an arms embargo.EU foreign ministers meeting to find a common response to the mounting crisis in Ukraine were to consider what measures to take in the event of “further possible negative actions by Russia,” according to a draft of the final statement seen by AFP. “In the absence of an agreed solution, the EU will consider/begin preparations for future targeted measures, including an arms embargo,” it said.This section of the draft was in brackets, meaning it is open to change or even removal at the meeting.Russia and France in 2011 signed a contract worth over a billion euros for Moscow to buy two Mistral warships, its first ever purchase of military hardware from a NATO member.The first warship was floated out late last year and is set to be delivered to the Russian navy in October, with the second still under construction.