EU urges swifter Brexit talks as London seeks 'flexibility'

By Gabriela Baczynska and Alastair MacdonaldBRUSSELS (Reuters) - The European Union's chief negotiator Michel Barnier said on Monday he was concerned at the slow progress of Brexit talks, while his British counterpart David Davis called for "imagination and flexibility" to move on.British officials arrived in Brussels on Monday hoping to push the EU towards talks about their post-Brexit ties, which the bloc refuses to launch until there is agreement on London's exit bill and other pressing "divo