Russian soldiers have surrounded rebels in the southern Chechen village of Komsomolskoye, who are fighting on despite earlier promises to surrender.
The commanders say several dozens rebels are holding out and have attempted to slip past Russian positions to escape to the mountains but so far have failed.
Capturing the village, which is now in ruins after two weeks of fighting, is crucial to the Russian war campaign, as it lies at the entrance to a strategic gorge.
Russia, which says the war in Chechnya is winding down, has raised its flag over what is left of Komsomolskoye.
On Monday the remaining rebels offered a ceasefire which the Russian troops refused to negotiate and a few hours later 76 armed fighters surrendered.
The field commander Ruslan Gelayev was not among those who surrendered - his whereabouts are unknown, and no-one is even sure if he is alive or dead.
Now some 150 rebels who originally agreed to surrender are thought to remain holed up in the village with no escape route.
The Russian army says that 500 to 600 rebels and up to 50 Russian soldiers have been killed during the fighting for Komsomolskoye which has lasted for two weeks.
The bodies of dead rebels confirm it as one of the most desperate battles of the war yet.
On Wednesday Russian troops were seen deploying tanks and artillery in Komsomolskoye in what is being called "a tough mopping-up operation."
Russian officers say the rebels' resistance is pointless.
"They went in attack here in a totally suicidal manner. In the first wave Gelayev (rebel commander in Komsomolskoye) sent his least trained men who he did not really need. They just kept on moving forward and were getting killed in scores by land mines and gunfire. But in their attack they wiped out our grenade launcher team as well. Then new waves of rebels came to replace those killed and again they were mowed by our fire."
SUPER CAPTION: Russian Officer
Russia's intense air and ground bombardment has driven all the civilian residents from their homes.
On Monday acting President Vladimir Putin said on a surprise trip to Chechnya that he would negotiate with the rebels if they gave up their weapons.
Separatist fighters have carried a number of ambush attacks well inside Russian lines this month, claiming to have taken 100 soldiers' lives.
A rebel website says that 70 Russians died in an ambush on Sunday near Shatoi, deep in the southern mountains, but Russia has refused to comment.
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Jul 21, 2015