EU "must sign a new agreement" with Ukraine: Cameron European leaders prepared on Thursday to debate biting economic sanctions against Russia for its annexation of Crimea as Ukraine tore up key ties with the Kremlin and drew up plans to evacuate its nationals from the rebel peninsula. British Prime Minister David Cameron said "one of the things we must do at this council is sign a new agreement, with the Ukraine, offering them a prosper future, access to our markets and real political support." Images and soundbites of David CameronREFILING TO CORRECT SOURCE: AFPTV