UN Secretary-General Ban Ki-moon urged Ukraine and Russia on Friday to meet for talks to prevent the crisis between them becoming "uncontrollable" and spreading beyond the region.
"What is important at this time is for Ukrainian and Russian authorities to sit down together and engage in direct and constructive dialogue," Ban said in the Ukrainian capital Kiev after meeting acting President Oleksander Turchinov.
His visit follows a meeting with Russian President Vladimir Putin in Moscow on Thursday, where he also called for dialogue and restraint after Russia's annexation of Ukraine's Russian-majority region of Crimea. This has brought about the worst confrontation between Moscow and the West since the Cold War.
In Kiev, Ban said the longer peaceful dialogue was delayed, "the greater risk there will be of uncontrollable situations beyond these two countries and beyond the region."
Turchinov said Ukraine was willing to hold talks, but it would never accept the annexation of Crimea.
"We stand ready to begin negotiations with Russia in any kind of format, but the main topic ... should be the full withdrawal of Russian troops from Ukrainian territory," he said at a joint press conference with Ban after their meeting.
Earlier in the day, in defiance of these sentiments and Western leaders who say the Black Sea peninsula remains part of Ukraine, Putin signed legislation that completed the process of absorbing Crimea into Russia.
(Reporting by Pavel Polityuk, Writing by Alessandra Prentice, Editing by Alissa de Carbonnel and Mark Heinrich)