The UN Security Council has ruled that a free and fair presidential election run-off in Zimbabwe is impossible.The council - including South Africa, China and Russia which have previously long opposed discussion on Zimbabwe - made the unanimous decision just hours after it emerged that opposition leader Morgan Tsvangirai has taken refuge in the Dutch embassy in Harare.In New York, the non-binding statement of the 15-nation body said: "The Security Council regrets that the campaign of violence and the restrictions on the political opposition have made it impossible for a free and fair election to take place on June 27."Mr Tsvangirai reacted to the ruling saying: "I think it's a very important resolution. It recognises the people who are accountable for the violence, and it squarely placed that responsibility at Mugabe's leadership...I am sure that he can no longer remain defiant to that international position."He repeated that he would not be participating in the election, saying: "It's ridiculous to go into an election of that kind. It's a one-man competition."Mr Tsvangirai, who at the weekend withdrew from Friday's run-off, has not requested asylum but spent Sunday night in the embassy and is welcome to stay for his own security, officials from the Netherlands said.The UN statement had been watered down from an earlier British-drafted version, which blamed President Robert Mugabe's government for the crisis and said Mr Tsvangirai would be the legitimate leader if a credible run-off vote could not be held.But the final version, said the council, "notes that the results of the (March 29 elections) must be respected." Mr Tsvangirai won that first-round, though the government said his narrow victory meant a run-off was necessary.In his strongest comments on Zimbabwe, UN Secretary-General Ban Ki Moon told reporters: "There has been too much violence and too much intimidation." The opposition says nearly 90 of its supporters have been killed.South Africa, an advocate of "quiet diplomacy" with Mr Mugabe, said it was "very pleased" with the statement because it "assists us in the mediation". Pretoria has resisted calls to use its powerful economic leverage over landlocked Zimbabwe.The UN ruling echoed mounting international concern over Zimbabwe's political turmoil and economic meltdown, blamed by the West and the opposition on Mr Mugabe, 84, who has held power for 28 years.Mr Mugabe's government said the election would still go ahead on Friday and the Zimbabwean leader repeated accusations that former colonial power Britain and other Western countries were lying about the violence because they wanted to interfere.Mr Mugabe was quoted by state-controlled media as saying at a rally on Monday: "Britain and her allies are telling a lot of lies about Zimbabwe, saying a lot of people are dying. They want to build a situation to justify their intervention."Mr Tsvangirai's Movement for Democratic Change said police raided its Harare offices and took away more than 60 victims of violence sheltering there, including women and children.When he announced his withdrawal on Sunday, Mr Tsvangirai said his supporters would have been risking their lives if they had voted but that he was ready to negotiate with Mr Mugabe's ZANU-PF party if the violence stopped.The political and economic crisis in Zimbabwe has sent millions of refugees flooding into neighbouring countries.