Germany's foreign minister warned on Friday that the situation in Ukraine's separatist east was turning more "fragile" and that negotiators must focus their efforts on averting a further deterioration.

"The situation in east Ukraine is once again becoming fragile," Frank-Walter Steinmeier told reporters after holding talks with Ukrainian Prime Minister Arseniy Yatsenyuk, stressing the need to consider "all options" to avoid a "deterioration" in the conflict zone.