The foreign ministers of Germany, France, Russia and Ukraine met Friday in Berlin to further discuss steps required to end the conflict in east Ukraine.
Germany‘s Frank-Walter Steinmeier said: "We can be glad that the ceasefire regime has been observed to a certain extent." He said " the progress has been made, but some serious challenges" remained, including organizing fair local elections in separatist-held areas.
Also in attendance at the Villa Borsig, in north-west Berlin were France's Laurent Fabius, Russia's Sergei Lavrov and Ukraine's Pavlo Klimkin.
A ceasefire between Ukrainian government troops and Russian-backed separatists in the east has largely held since September.
The chief international monitor in Ukraine, Ertugrul Apakan, said this week in Vienna that the light weapons removal was advancing, but added that "weapons of all calibres continue being used" in sporadic ceasefire violations.
"The situation remains volatile," the head of the monitors of the Organization for Security and Co-operation in Europe (OSCE) told reporters.
In addition, he highlighted de-mining eastern Ukrainian areas as another key step that should be taken soon. OSCE observers would define and map priority areas for removing mines, Apakan said.
Germany has urged more effort to resolve the conflict on a political level, including a constitutional reform and granting unfettered access of OSCE monitors to the entire conflict region.