By Alessandra Prentice and Andreas Rinke
KIEV/RIGA (Reuters) - German Foreign Minister Frank-Walter Steinmeier said on Tuesday he saw hope for a lasting ceasefire in eastern Ukraine, while Kiev announced the deaths of three soldiers killed fighting separatist rebels in the past 24 hours.
Steinmeier was speaking on the eve of a visit to Kiev together with his French counterpart Jean-Marc Ayrault, who will hold joint talks with Ukrainian President Petro Poroshenko.
Ukraine and the rebels had agreed a truce to coincide with the start of a new school year on Sept. 1 - a ceasefire that was broadly respected until the recent reported rise in attacks.
Steinmeier said the truce, fragile as it was, showed it was possible to improve the situation, and was encouraged after talks with his Ukrainian and Russian counterparts.
"That is why I believe, after my discussions with Pavlo Klimkin in Berlin and Sergei Lavrov yesterday, that it is now possible to agree on a durable ceasefire, without preconditions," he said on a visit to Riga.
He said Germany and France had made proposals for achieving a new ceasefire and starting the political process required to reach a lasting peace.
Ukraine and the West accuse Moscow of fomenting a pro-Russian rebellion in the east of the country; but Russia denies the accusation.
The Minsk peace agreement, originally agreed between Russia, Ukraine, Germany and France in September, 2014, has helped considerably reduce fighting in the industrial Donbass region.
But violations have occurred regularly and implementing further points of the plan, including holding regional elections and returning control of Ukraine's border with Russia to Kiev, has long stalled.
The Ukrainian soldiers were the first to die in open fighting this month. Ukrainian military spokesman Oleksandr Motuzyanyk said over the past day separatists had also used heavy weapons for the first time this month and directly attacked a Ukrainian position in the Luhansk region.
"A sabotage-and-reconnaissance group crossed the river and attacked our servicemen. The fight lasted for 15 minutes," Motuzyanyk said in a daily televised briefing.
Rebel leaders denied violating the truce, accusing the Ukrainians of attacking rebel positions. They said separatist forces would observe a new unilateral ceasefire, starting at midnight on Sept. 15.
"I call on the Ukrainian side to take this seriously and show that they are prepared to do this rather than merely paying lip service," Donetsk rebel leader Alexander Zakharchenko said in a statement on Russian television channel Rossiya-24.
(Additional reporting by Andrea Shalal in Berlin; Editing by Matthias Williams and Ralph Boulton)