The French foreign minister says "quite a number of problems remain" in negotiations aimed at ending fighting in eastern Ukraine.

Laurent Fabius told France Inter radio that just hours before a four-way summit Wednesday in Minsk, Belarus, it was "very probable" but not certain that French President Francois Hollande would attend.

Fabius said difficulties remain on the future of embattled eastern Ukraine, guarantees about the Ukraine-Russia border near the area, and the prospects of a possible cease-fire, weapons pullback and prisoner exchange.

Fabius said the aim of the talks is to win an accord, but "not just one on paper."

Hollande and German Chancellor Angela Merkel are mediating talks between Ukrainian President Petro Poroshenko and Russian President Vladimir Putin.