(Adds Chinese comment, paragraph 12, edits)
By Patrick Worsnip
UNITED NATIONS, July 11 (Reuters) - Russia and China vetoed on Friday a Western-backed U.N. Security Council resolution to impose sanctions on Zimbabwe for holding a violent presidential poll that was boycotted by the opposition candidate.
The resolution would have imposed an arms embargo on the southern African country and financial and travel restrictions on President Robert Mugabe and 13 other officials, and called for a U.N. special envoy for Zimbabwe to be appointed.
Nine countries voted for the U.S.-drafted text, five -- including veto-holding Russia and China -- opposed it and one abstained in the 15-nation council.
The result marked a failure by the Western bloc to induce Russia and China to at least abstain because of the gravity of the crisis in Zimbabwe. It also sparked angry exchanges between the big powers.
U.S. Ambassador Zalmay Khalilzad accused Russia of a "U-turn" from its position at a Group of Eight summit in Japan earlier this week, when Moscow joined a statement backing sanctions against Mugabe’s government.
Russia’s performance on Zimbabwe "raises doubts about its reliability as a G8 partner," Khalilzad told the council.
Opponents of the resolution, which also included South Africa, Libya and Vietnam, argued that Zimbabwe was not a threat to international peace and security -- the qualification for council action.
They said imposing sanctions over an election was interference in Zimbabwe’s internal affairs and called for current talks in South Africa between the country’s ruling and opposition parties to be given a chance.
But British Ambassador John Sawers told the council it had "failed to shoulder its responsibility to do what it can to prevent a national tragedy deepening and spreading its effects across southern Africa."
He called the Russian and Chinese decisions "deeply damaging to the long-term interests of Zimbabwe’s people ... (and to) prospects for bringing to an early end the violence and the oppression in Zimbabwe."
Russian Ambassador Vitaly Churkin responded that the resolution was "an ever more obvious attempt to take the council beyond its charter prerogatives and beyond maintaining international peace and security. We believe such practices to be illegitimate and dangerous."
Chinese Ambassador Wang Guangya told reporters before the vote Beijing could not accept the language of the resolution and wanted dialogue between Zimbabwe’s parties, "so to adopt such a resolution at this time would not be helpful."
Zimbabwean Ambassador Boniface Chidyausiku said the Security Council had refused to be "intimidated" by Britain -- former colonial ruler of Zimbabwe -- and the United States. "The United Nations has stuck to the Charter," he said.
Voting for the resolution were the United States, Britain, France, Italy, Belgium, Croatia, Burkina Faso, Panama and Costa Rica. Indonesia abstained.
In Zimbabwe, the opposition on Friday accused government security forces of murdering a polling agent in fresh political violence that could undermine the talks in South Africa.
Movement for Democratic Change leader Morgan Tsvangirai withdrew from a June 27 presidential run-off poll, citing attacks on his supporters by pro-Mugabe militia. The MDC and Western powers branded Mugabe’s landslide re-election a sham.
Tsvangirai’s MDC and a smaller faction began preliminary discussions on Thursday with officials from Mugabe’s ruling ZANU-PF under the auspices of South African mediators in Pretoria, the South African capital.
"Yes, the talks are continuing," a diplomatic source close to the talks told Reuters on Friday. The MDC has played down the importance of the talks.
Party spokesman Nelson Chamisa said there had so far been no real dialogue, merely "consultative contacts" aimed at outlining a framework for negotiation.
A total of 113 MDC activists have been killed in election-related violence since the first round of elections in late March, the party said in a statement announcing the death of one of its officials, Gift Mutsvungunu.
His decomposing body was found in a Harare suburb on Thursday, with eyes gouged out and a severely burned backside, it said. "There is reasonable suspicion that state security agents killed him."
Tsvangirai defeated Mugabe in a March 29 presidential election but failed to win the absolute majority needed to avoid a second ballot. The MDC leader has refused to negotiate a power-sharing deal until the government halts the bloodshed.
Once prosperous Zimbabwe has the world’s worst inflation rate, estimated to be at least 2 million percent. Millions of people have fled to neighboring states to seek food and work. (Additional reporting by MacDonald Dzirutwe in Harare, Muchena Zigomo in Pretoria and Ellen Wulfhorst at the United Nations; Editing by Eric Beech)