Congolese government troops have entered the eastern border town of Bunagana as M23 rebels abandoned what was the last significant town they were holding.
The town was first seized by the rebels last year and its loss is the latest success in an offensive by Democratic Republic of Congo's UN-backed army, which is seeking to crush a 20-month rebellion.
Al Jazeera's Malcolm Webb, reporting from Bunagana, said the town was deserted when government forces swept in because civilians and rebels had fled fearing the advance.
“The civilians came running back when they saw the army come in,” said Webb, who was travelling with government forces. “Now, it's a very jubilant mood. People were cheering and hugging the soldiers.”
Celebrating soldiers shouted and high-fived for the cameras, giving martial arts demonstrations and performing dramatic dance moves in the centre of the town, surrounded by dozens of laughing locals.
But the heavy fighting that erupted as they closed in on some of the last pockets of territory held by the rebels has forced more than 10,000 Congolese to flee into Uganda, officials and humanitarian workers have said.
Lucy Beck, a spokeswoman for the UN refugee agency in Uganda, said the Congolese crossing the border were now “too many to count”. The number of Congolese seeking refuge in Uganda rose from 5,000 to more than 10,000 within hours on Wednesday, she said.
Among those crossing the border on Wednesday was Bertrand Bisimwa, the civilian head of the M23 movement, who was reported to be on his way to the Ugandan capital, Kampala, at the request of a mediator trying to bring an end to the 18-month rebellion, according to Uganda's top military spokesman.
Bisimwa does not face arrest in Uganda, which has been mediating failed peace talks between the Congolese government troops and the M23 since December, said Uganda Lt Colonel Paddy Ankunda.
The talks stalled again earlier this month and, within days, clashes erupted between Congolese forces and the rebels.
The M23 emerged in April 2012, the latest incarnation of an ethnic Tutsi rebel group dissatisfied with the Congolese government.
Neighboring Rwanda, whose president is also an ethnic Tutsi, is widely believed to have provided weapons, recruits and training to the M23.
Rwanda's government has denied the allegations, saying Congo's government has failed to police its territory.
M23 briefly overtook Goma - a city of 1 million people - last November but has been substantially weakened in the past year by internal divisions and waning Rwandan support, according to a United Nations group of experts.