BRASïLIA - Ukraine’s leader has accepted an invitation to attend Sunday’s World Cup final, with Russian President Vladimir Putin also among the spectators, amid a crisis between their countries, Brazilian officials said.‘The president of Ukraine (Petro Poroshenko) confirmed Friday that he will go to the final,’ a Brazilian presidency spokesman told AFP on Saturday. A foreign ministry spokesman said the Ukrainian and Russian heads of state would attend a lunch hosted by President Dilma Rousseff with other foreign leaders, including German Chancellor Angela Merkel, before the Germany-Argentina game at Rio de Janeiro’s Maracana Stadium.However, Brazilian officials said they did not know whether the Ukrainian and Russian presidents would hold bilateral talks. Putin, whose country will host the 2018 World Cup, confirmed his attendance weeks ago. He will also attend a summit of the BRICS group of emerging powers in the northeastern city of Fortaleza on Tuesday.Merkel, who is also attending the match, will likely meet with Putin in Rio. In late June, the Russian and Ukrainian leaders held four-way telephone talks with Merkel and French President Francois Hollande in a bid to secure a truce between Kiev and pro-Russian separatists in the east of Ukraine. Kiev and its Western allies accuse Moscow of both arming and funding the militias in a bid to unsettle the new Ukrainian government as revenge for the February ouster of a pro-Kremlin president. On Saturday, panicked Ukrainians flooded highways and packed trains leading out of the main remaining rebel stronghold, fearing a reprisal assault by government forces after they lost 30 servicemen to defiant militants.Separatists near the Russian border mowed down 19 troops in a hail of heavy rocket fire on Friday in a bloody reminder of their resolve to reverse the recent tide of government gains across the country’s eastern rustbelt. The military said four other troops died elsewhere on Friday and seven more were killed overnight in attacks that also wounded more than 120 soldiers. Ukraine’s new Western-backed leader immediately vowed to hunt down the guilty militias in a push that would shatter all hopes of a truce in one of Europe’s most explosive conflicts in decades.‘The rebels will pay for the life of every one of our servicemen with tens and hundred of their own,’ Poroshenko told an emergency security meeting. The militant talk convinced many in the million-strong eastern hub of Donetsk - the new home to a flood of gunmen who had abandoned surrounding cities since last weekend - that their riverside city was about to be bombed. A week ago, Poroshenko had proclaimed the seizure of Slavyansk - the symbolic heart of the uprising - a turning point in a conflict set off by the ouster in Kiev of president Viktor Yanukovych and Russia’s subsequent seizure of Crimea. European Union leaders quickly joined Russia in a rare collective bid to dampen Kiev’s new-found bravado and convince Poroshenko to launch direct truce talks with the separatists.