Fresh fighting has erupted in the east of the Democratic Republic of Congo as government forces try to clear the last areas held by M23 rebels.
The BBC's Ignatius Bahizi in the border town of Bunagana says missiles are being fired and thousands of refugees have fled into Uganda.
The M23 on Sunday called a ceasefire to allow peace talks with the government to continue.
However, our reporter says there is no sign a ceasefire has taken effect.
He says the mood on the border is very tense.
Continue reading the main story [h=2]Analysis[/h] Moses Rono BBC Africa security correspondent
The imminent defeat of DR Congo's M23 rebels is the result of shifting military and political dynamics that present the most concrete prospects of peace in the unstable central African nation.
Its defeat would send an intimidating message to at least 10 other rebel groups operating in the area, raising hopes that a lasting peace for the mineral-rich nation may finally be in sight.
The M23 rebels were routed from its main bases by DR Congo's army, a force generally known for its indiscipline, inefficiency and corruption.
When the M23 took control of Goma in November 2012 it embarrassed the government and put pressure on the international community after human rights violations emerged.
President Joseph Kabila made changes to the military hierarchy and troops fighting in the east.
In a sign that these changes might have started working, no reports of human rights violations blamed on Congolese army have emerged, unlike during previous operations.
Other BBC correspondents in the area say the rebels seem to be fighting back more fiercely than on previous days.
Shells fired by the M23 have fallen on both sides of the border which runs through Bunagana, with at least four people killed in DR Congo, various sources have told the BBC.
The BBC's Ignatius Bahizi in the border town of Bunagana says missiles are being fired and thousands of refugees have fled into Uganda.
The M23 on Sunday called a ceasefire to allow peace talks with the government to continue.
However, our reporter says there is no sign a ceasefire has taken effect.
He says the mood on the border is very tense.
Continue reading the main story [h=2]Analysis[/h] Moses Rono BBC Africa security correspondent
The imminent defeat of DR Congo's M23 rebels is the result of shifting military and political dynamics that present the most concrete prospects of peace in the unstable central African nation.
Its defeat would send an intimidating message to at least 10 other rebel groups operating in the area, raising hopes that a lasting peace for the mineral-rich nation may finally be in sight.
The M23 rebels were routed from its main bases by DR Congo's army, a force generally known for its indiscipline, inefficiency and corruption.
When the M23 took control of Goma in November 2012 it embarrassed the government and put pressure on the international community after human rights violations emerged.
President Joseph Kabila made changes to the military hierarchy and troops fighting in the east.
In a sign that these changes might have started working, no reports of human rights violations blamed on Congolese army have emerged, unlike during previous operations.
Other BBC correspondents in the area say the rebels seem to be fighting back more fiercely than on previous days.
Shells fired by the M23 have fallen on both sides of the border which runs through Bunagana, with at least four people killed in DR Congo, various sources have told the BBC.
