EU wields Russia sanctions threat but timing vague

Finland's Prime Minister Alexander Stubb (L-R), Denmark's Prime Minister Helle Thorning-Schmidt, German Chancellor Angela Merkel and Bulgaria's President Rosen Plevneliev hold a discussion at the start of a European Union summit in Brussels August 30, 2014. REUTERS/Yves Herman

BRUSSELS (Reuters) - The European Union threatened Russia with new trade sanctions if Moscow fails to start reversing its action in Ukraine, but sharp divisions among leaders at a summit in Brussels left the timing of any measures uncertain.

After a lengthy briefing by Ukrainian President Petro Poroshenko, who warned "full-scale war" was imminent if Russian troops continued an advance in support of pro-Moscow rebels, the leaders agreed on Sunday to have EU officials draw up within a week a list of new measures that could hit a range of sectors.