By Pavel Polityuk and Oleksandr Kozhukhar KYIV/LVIV (Reuters) – EU leaders agreed on Monday to ban most imports of Russian oil to the 27-nation bloc as Ukrainian and Russian forces battled on the outskirts of Sievierodonetsk, the last city still held by Kyiv in Ukraine’s strategic Luhansk province. European Council President Charles Michel said on Twitter the ban, agreed at an EU summit in Brussels, would immediately cover more than two thirds of oil imports from Russia “cutting a huge source of financing for its war machine.” EU leaders meeting in Brussels also agreed to cut off the largest R…