Kiev (AFP) - Seven Ukrainian soldiers have died in the country's war-torn east over the past 24 hours, the biggest casualty toll in a single day this year, Kiev said on Tuesday.
The latest violence came as the leaders of France, Germany, Russia and Ukraine called for the implementation of a peace deal in the separatist east during late-night talks on Monday.
Ukraine also called for an OSCE "police mission" while the Kremlin said it backed an expanded monitoring mission in the east of Ukraine.
"As a result of shelling, seven Ukrainian soldiers have died and nine received injuries over the past 24 hours," Oleksandr Turchynov, secretary of Ukraine's National Security and Defence Council, said in a statement.
Turchynov blamed Russia's leadership for the attacks, accusing it of doing everything to "torpedo a peaceful way to solve the conflict and the liberation of the occupied territories".
He claimed Russia was massing heavy weapons along a demarcation line in the east, adding that over the past month Ukraine had detected an increased number of Russian reconnaissance and other unmanned aerial vehicles.
Military spokesman Oleksandr Motuzyanyk said the deaths represented "extremely heavy losses" for the Ukrainian forces.
On Monday, the leaders of France, Germany, Russia and Ukraine spoke by phone and called for the 2015 peace accords signed in Minsk to be implemented "as quickly as possible," according to the office of French President Francois Hollande.
The accords call for a ceasefire along with a range of political, economic and social measures to end the conflict which erupted in April 2014 and has now claimed more than 9,300 lives.
The Kremlin said that Germany, France and Ukraine had received proposals concerning local elections in the rebel east, the regions' special status and decentralisation, noting they had been agreed with pro-Russian insurgents.
- OSCE police mission? -
Persistent violence is preventing the warring sides from reaching a firm political reconciliation deal despite a series of truce agreements that have helped reduce the fighting over the past months.
Poroshenko's office said that the leaders of Ukraine, France, Germany and Russia expressed support for the deployment of an OSCE police mission to eastern Ukraine and the start of consultations on the subject.
OSCE declined immediate comment, while the Kremlin indicated that it did not see eye to eye with Ukraine on the subject.
"In our understanding, this is not a police mission," Kremlin spokesman Dmitry Peskov told reporters on Tuesday of the OSCE monitors in east Ukraine.
But he said that "indeed this subject is being discussed," noting that the mission's arms policy was under question.
"We are talking about a demarcation line. The agreement of rebels is important here. We are talking about a demarcation line between rebel forces and Ukraine's armed forces and not about control over the Russian-Ukrainian border," Peskov said.
Political observers were hard-pressed to interpret the results of the nighttime talks.
"It is clear that nothing is clear," Olga Aivazovska, head of the board of Ukraine's civil network OPORA, said on Facebook.
"Ukraine needs such a mission but its mandate should not only include the functions of a police mandate but also be efficient when it comes to its duration and the numbers," she added.
Earlier this month, France and Germany held a round of talks with Kiev and Moscow as part of efforts to try to seek a lasting peace deal but no consensus was reached on elections in the separatist regions.
Kiev and the West have accused Russia of buttressing the rebels and sending regular troops across the border, claims Moscow has repeatedly denied.
Ukrainian Defence Minister Stepan Poltorak warned last month that it could take years to end the conflict.