Germany's Foreign Minister Frank-Walter Steinmeier said Saturday that a meeting with his Russian, Ukrainian and French counterparts had yielded "significant progress" and expressed hope on an agreement to withdraw heavy weapons from eastern Ukraine.

"We all reaffirmed that the ceasefire which has been kept for two weeks now needs to be further consolidated and secured," Steinmeier said Saturday in a statement.

Despite a cease-fire declared in February, the Ukrainian military and Russia-backed separatists have carried out regular artillery strikes up until a recent truce that's been holding since September 1, the first day of school.

"It's all still very fragile," Steinmeier said.

OSCE Secretary-General Lamberto Zannier said he had just returned from the southeastern city of Mariupol and nearby Shyrokyne, the site of recent clashes, and the situation remains quiet and calm.

"So the ceasefire now has being holding for more than 10 days and that's good news, because that is opening now the space to make progress on a political level," Zannier told The Associated Press on Saturday.

In Moscow, Russian President Vladimir Putin on Saturday referred to the ceasefire as the "main achievement" of efforts to find a peaceful solution to the crisis in eastern Ukraine.

The ministerial-level talks held Saturday in Berlin were ahead of a planned summit of the four nations' leaders on October 2 in Paris. The Minsk ceasefire agreement, signed in February in the Belarusian capital, is due to be fully implemented by the end of the year.

Challenges lie ahead

Separatist leaders in the two rebel-held regions have announced plans to hold their own elections on October 18 and November 1. The Kyiv government says an election by separatist authorities would violate the ceasefire pact.

Besides calling for the full cessation of hostilities, the Minsk agreement requires the withdrawal of large-caliber weapons from 50 kilometers (31 miles) from the front lines dividing Ukrainian and separatist forces, as well as thorny issues such as granting Ukraine full control of its eastern border with Russia.

Kyiv has also pledged to devolve power in eastern Ukraine, though local elections remain a thorny issue.

The German foreign minister said that the four nations agreed - in principle - that local elections should be held on a joint legal basis between Kyiv and separatist leaders and would have to be monitored by OSCE election observers.

Large-scale fighting between separatists in eastern Ukraine and the Ukrainian military broke out in April 2014. Some 8,000 lives have been lost, according to the United Nations.

jar/bw (AP, dpa)