By Guy Faulconbridge and Max Hunder MOSCOW/KYIV (Reuters) -On the eve of peace talks, Ukraine and Russia sharply ramped up the war with one of the biggest drone battles of their conflict, a Russian highway bridge blown up over a passenger train and an ambitious attack on nuclear-capable bombers deep in Siberia.

Since last sitting down with Ukraine to talk peace, Russia has launched four of its five largest drone attacks against the country, killed more than 340 of its civilians and continued to peddle its false narrative about the unprovoked war it has been waging for more than a decade.

Ukraine will send a delegation to Istanbul for a new round of direct peace talks with Russia on Monday, President Volodymyr Zelensky announced Sunday, as the conflict rages on with deadly missile strikes and the largest drone assault of the three-year war.