CANADA STOCKS-TSX may open flat on Ukraine concerns; Yellen in focus

Feb 27 (Reuters) - Canadian stock index futures pointed to a flat open on Thursday as concerns over escalating political and military tension in Ukraine and Russia kept investors on the edge. Markets will also watch for U.S. Federal Reserve Chair Janet Yellen's testimony later in the day. TOP STORIES * In Ukraine's Crimea, armed men seized the regional government headquarters and parliament and raised the Russian flag, alarming Kiev's new rulers, who urged Moscow not to abuse its navy base righ