Serbia on Saturday asked Russia to veto a British U.N. Security Council resolution that would call the massacre of some 8,000 Muslim men and boys during the Bosnian war in Srebrenica genocide. The U.N. Security Council will vote the resolution on July 7. Serbian state TV said the country's pro-Russian President Tomislav Nikolic has sent a letter to Russian President Vladimir Putin "pleading" for a Russian "no" in the U.N. council when the resolution is expected to be tabled next week.Western nations and Russia have been dueling in the U.N. over whether the killings should be called genocide or not. Russia, which has close historic and religious ties to Serbia, has circulated a rival draft resolution which doesn't mention either Srebrenica or genocide.The British resolution was intended to commemorate the 20th anniversary of the July 1995 slaughter. U.N. courts have labeled it genocide. Serbian officials say the resolution should include all victims of the Bosnian civil war that pitted Christian Orthodox Serbs against the Bosnian Muslims and Croat Catholics. Nikolic's move also reflects political divisions in Serbia among those who seek closer ties with the European Union and his pro-Russian faction that want Serbia in the Kremlin orbit. Serbia's prime minister Aleksandar Vucic, a former extreme nationalist who now declares himself as pro-EU, has said he is ready to attend memorial ceremonies marking the Srebrenica anniversary in Srebrenica but also has refused to call it genocide.Following the British-drafted resolution commemorating the 1995 Srebrenica massacre, The British-drafted resolution has angered Bosnian Serbs and Serbia, who branded it as "anti-Serb" and sent a letter of protest to the United Nations. The British draft strongly condemns the genocide at Srebrenica and any denial of this genocide, while the Russian text instead condemns "the most serious crimes of concern to the international committee."The U.N. Secretary General Ban Ki-moon on Wednesday admitted the U.N. failed in its duty to protect the victims of the 1995 Srebrenica massacre. "The UN Secretariat, the Security Council and member states share the blame," Ban said at an event in New York to commemorate the 8,000 Muslims murdered by Serb paramilitaries in the Bosnian town while under the protection of UN peacekeepers. Ban said the "atrocious murder of Muslim men and boys in Srebrenica will forever weigh on the collective conscience of the international community." Recalling a 2012 visit to Bosnia, Ban told how the "endless rows of tombstones is now etched in my mind" and said he would "always remember the tears and pain of the mothers and loved ones of those who were killed because of who they were."On July 11, 1995, towards the end of Bosnia's 1992-95 war, Bosnian Serb forces swept into the eastern Srebrenica enclave, a U.N.-designated "safe haven." 8,000 Muslim men and boys were executed in the days that followed, dumping their bodies into pits.Serbia acknowledges that a "grave crime" took place and adopted a declaration condemning the massacre in 2010 as it sought closer ties with the West, but stopped short of describing it as genocide. Its president at the time, Boris Tadic, attended the 15th anniversary commemoration.The U.N. war crimes tribunal for the former Yugoslavia has ruled the worst mass killing on European soil since World War Two was genocide.