Foreign ministers from Germany, France, Russia and Ukraine call for an end to fighting amid a sharp uptick in hostilities

(Reuters) BERLIN — Foreign ministers from Germany, France, Russia and Ukraine have called for an end to the renewed heavy fighting in eastern Ukraine following tough talks in Berlin.

German Foreign Minister Frank-Walter Steinmeier told reporters on Monday that the talks had been "at times very controversial" but said all participants agreed there was no alternative to the cease-fire agreement signed in the Belarusian capital Minsk in February.

French Foreign Minister Laurent Fabius, Ukrainian Foreign Minister Pavlo Klimkin, German Foreign Minister Frank-Walter Steinmeier and Russian Foreign Minister Sergei Lavrov, April 13, 2015.

"We need to ensure that the cease-fire is adhered to far more strongly as fully as possible," Steinmeier said.

The talks took place amid a sharp spike in hostilities in eastern Ukraine over the weekend. On Monday one Ukrainian serviceman was killed and six were wounded in rebel-held territories.

Steinmeier said all parties had agreed to push ahead with the withdrawal of heavy weapons from the front line and to extend this to other categories of weapons, including tanks, armoured vehicles and heavy weapons smaller than 100 mm calibre.

The foreign ministers were also all willing to support the Organisation for Security and Cooperation in Europe (OSCE), which is monitoring the implementation of the cease-fire deal, further with money and personnel over the next few weeks.

They also agreed to continue with an exchange of prisoners in the conflict region and to set up four working groups to deal with the humanitarian, economic and security policy questions in east Ukraine.

Steimeier stressed, however, that the Minsk accord went beyond the cease-fire agreement and must pave the way towards elections in the rebel-held territories.

"If this process stalls, then the Minsk agreement risks possibly coming off the rails … all sides wants to prevent this," he said.