Foreign ministers from the Normandy Quartet countries have called on the trilateral Contact Group for Ukraine to agree a schedule for the withdrawal of weapons below a 100 mm caliber from the line of contact in Donbas, the chair of the Normandy format's ministerial meeting in Berlin said in a statement.

"We furthermore call for the withdrawal of mortars and heavy weapons below 100mm as well as all types of tanks. We call upon the Trilateral Contact Group in consultation with SMM (Organization for Security and Cooperation in Europe Special Monitoring Mission) and JCCC (Joint Center for Control and Coordination) to agree on a relevant schedule," according to the statement.

"We also strongly call on the sides to be fully cooperative on the verification process," the document says.

At their meeting in Berlin, the foreign ministers of Germany, France, Russia and Ukraine also noted that "the situation remains tense because of numerous violations."

"In particular, we expressed our grave concern at the recent outbreak of fights over the last weekend, including the use of heavy weapons around Shyrokyne and Donetsk Airport," the statement says.

"We call on all sides to stop fighting and demonstrate their commitment to fully implementing the ceasefire and conclude the withdrawal of heavy weapons definitely," the document says.