Gerhard Schröder's office on Sunday refused to comment after Russian President Vladimir Putin said he would like the former German chancellor as a possible European mediator in peace talks to end the Ukraine war . Putin told reporters on Saturday: "Of all European politicians, I would prefer talks with Schröder." The ex-chancellor has maintained close relations with Moscow and is a personal friend of Putin. Speaking at the end of Victory Day celebrations, the Russian leader also said he thought the four-year conflict with Ukraine  was heading toward an end . In response to a question from DPA news agency, Schröder's office said it would not comment on the matter. On Sunday, news agencies cited anonymous German government officials as saying Putin's suggestion was "not credible" as Moscow had not altered its conditions for ending the war. The sources added that a first test of credibility would be for Russia to extend this weekend's 3-day ceasefire.…