A fighter with separatist self-proclaimed Donetsk People's Republic army stands on the roof of a building damaged by fighting in the village of Nikishine, south east of Debaltseve Feb. 17, 2015. Reuters/Baz Ratner

Ukrainian government troops trapped in the strategic city of Debaltseve are facing an increasingly dire situation as pro-Russian rebels advance, despite a ceasefire in effect since the weekend. Yuriy Sinkovsky, the deputy commander of Ukraine’s 40th Battalion, told a Ukrainian news source that the situation is "critical and outrageous" and that his forces are surrounded. Pro-Russian rebels claimed earlier in the day that they had taken the city, but according to Sinkovsky, the Ukrainian military hadn't surrendered. The government troops are “not going to retreat and give up,” he said, but he admitted that “enemy forces are much stronger.”

“[We’re] waiting for reinforcements from the General Staff or OSCE representatives,” said Sinkovsky, referring to the Organization for Security and Cooperation in Europe, which is supposed to check on the ceasefire, as stipulated by last week's Minsk agreement.

“Support has still failed to come," the Ukrainian officer said by phone, according to the newspaper. "Fighting is underway. There are prisoners. [The bodies of killed] and [wounded soldiers] cannot be evacuated from the checkpoints. The roads have been mined. All the rest [of my troops] are sitting, watching, waiting for the battalion to be killed."

The Ukrainian military and rebel forces both missed Tuesday's ceasefire-mandated deadline to withdraw heavy weaponry from areas around Debaltseve, with each side waiting for the other to act first.

Fighting stopped in most locations across eastern Ukraine when the ceasefire began at midnight on Sunday, but the fight for Debaltseve continued as Ukrainian troops defended the city from Russian-backed rebel rocket and artillery attacks. There were also reports of skirmishes in the port city of Mariupol.

The conflict in eastern Ukraine has seen more than 1 million people displaced and as many as 5,600 killed since it began more than 10 months ago, the United Nations said on Monday.

With the pro-Russian rebel-held regions of Luhansk just 80 kilometers (50 miles) to the east and Donetsk around the same distance to the west, Debaltseve has become the front line of the war between separatists and Ukrainian forces, because of its strategic value.

Ukraine Map
Debaltseve is directly between the two rebel-held strongholds of Donetsk and Luhansk. IBTimes/Google Maps

Debaltseve sits at the intersection of two major highways that connect the self-proclaimed separatist republics of Luhansk and Donetsk, but it also has an important rail hub that connects to stations deeper into the coal-rich Donbass region.

Immediately after the ceasefire agreement was signed, on Feb.12, fighting in and around the city increased dramatically, with rebel forces desperately looking to take the city before the ceasefire went into effect, on Sunday. When it became apparent that the city wouldn't fall before the deadline, fighting continued. Rebels said that because they had the city surrounded, it should be considered their territory in any post-ceasefire negotiation.

The Associated Press has reported that some Ukrainian soldiers have been taken prisoner, although it wasn't clear how many or what has happened to them since.

Reports suggest between 8,000 and 10,000 Ukrainian soldiers are in and around Debaltseve. Before the ceasefire came into force, pro-Russian rebels had said that Ukrainian troops would be given safe passage to leave the city. It’s yet to be seen whether that deal will be offered again.

Meanwhile, the battle for the city continues. According to the Ukraine government, rebel militants have launched more than 100 separate attacks on Debaltseve after the ceasefire was signed and five soldiers were killed in the past 24 hours.