KYIV, Jan 24 - Ukrainian and Russian negotiators began a second day of U.S.-brokered talks in Abu Dhabi on Saturday after an overnight wave of Russian airstrikes that knocked out power for millions of people amid freezing winter temperatures.

The strikes by hundreds of Russian drones and missiles on Kyiv and Ukraine's second largest city Kharkiv prompted Foreign Minister Andrii Sybiha - who was not present at the talks - to accuse Russian President Vladimir Putin of acting "cynically".