Donetsk airport saw fighting and shelling hit a hospital in the city Monday as Ukrainian officials charged that Russia had reinforced separatists. The military launched its latest counteroffensive against separatists on Saturday.

"We are not giving them the airport," Ukrainian military spokesman Andriy Lysenko said on Monday.

Kyiv agreed to a ceasefire with separatists in September, but both sides have regularly violated the deal since. Over the weekend, Russian officials said that President Vladimir Putin had offered a fresh peace proposal to his Ukrainian counterpart, Petro Poroshenko, but that the move had been rejected.

A contact group consisting of representatives from Russia, Ukraine, separatist leaders and the Organization for Security and Co-operation in Europe (OSCE), postponed talks which had been planned for last week. Proposed negotiations in Kazakhstan between Russian, Ukrainian, French and German leaders are also on ice, as no significant progress has been made in reining in the violence. Talks in Berlin on January 12 also saw no significant progress.

On Monday, German Foreign Minister Frank-Walter Steinmeier said that efforts to hold a summit among Russia, Ukraine, France and Germany would continue: "There is constant contact," he said.

Ukrainian officials allege that Russia has militarily supported separatists, charges Moscow denies. Lysenko said 700 troops had crossed the border into separatist-held territory on Monday alone.

"Two groups of armed forces from the Russian Federation crossed the border," Lysenko said on Monday.

'A concise task'

Intense clashes have followed the launch of the Ukrainian military's counteroffensive, with repeated heavy explosions ringing out from the area surrounding the Donetsk airport - with some also heard closer to the center of the city, less than a year ago the home to more than 1 million people. Despite the sporadic explosions, Monday has seen far less fighting than in recent days, when heavy clashes rocked the area around the airport, northwest of Donetsk, after Ukraine's military launched a major counteroffensive to push back the separatists.

"Our soldiers had a concise task: push back the rebels who were attacking us," military spokesman Vladislav Selezyov said Monday. "The 93rd Airport Brigade accomplished it."

Ukraine's military has reported at least three soldiers killed over the past 24 hours and another 66 wounded. Separatists have reported several civilian casualties,

According to the World Health Organization, the conflict has killed more than 4,800 people since April and has become Europe's worst humanitarian crisis since the Balkan wars of the 1990s. Separatists have disputed the military's official account and, with journalists rarely able to reach the conflict zone, independent confirmations of allegations by either side have been tough to come by.

mkg/bw (Reuters, AFP, dpa, AP)