AfricaNews Monitoring Team with files from BBC
Rebel fighters have entered central Goma, the main city in resource-rich eastern Democratic Republic of Congo.
The BBC's Gabriel Gatehouse in Goma says he saw them exchange some small arms fire with the Congolese army but they otherwise met little resistance.
The M23 rebels say they have captured the city, but this has not been confirmed.
Tens of thousands of people have fled recent fighting, which has led to fears of a resumption of the DR Congo war.
This is the first time since the war officially ended in 2003 that rebels have entered Goma, which has a population of about 400,000.
Talks rejected
Some five million people died in the war, which dragged in neighbouring states - including Rwanda, Uganda, Zimbabwe, Namibia and Angola.
Rwanda has denied persistent accusations that it backs the M23 rebels.
On Monday, it accused the Congolese army of deliberately firing across the border onto its territory.
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The commander of United Nations peacekeepers in DR Congo, Lt-Gen Chandar Prakash, said the rebels had tried to attack his forces at the airport, but had been repelled.
Some rebels had used the cover of civilian houses to bypass the UN base there and enter the town, he said.
Our correspondent says he understands that government forces are no longer at Goma's airport, but UN forces are still there.
The UN force has not tried to resist the rebel advance, and watched as about a dozen rebels marched past their armoured vehicles, our reporter adds.
He says the rebels have gone through Goma and have reached the border with Rwanda.
"The town of Goma fell at 11:33 local time [08.33GMT], despite the attack helicopters, despite the heavy weapons, the FARDC [Congolese army] has let the town fall into our hands," M23 spokesman Colonel Vianney Kazarama told Reuters news agency.
On Monday, the government rejected a 24-hour ultimatum by M23 to withdraw its forces from Goma and enter into peace talks.
It said it would defend the city and it would only hold talks with Rwanda, saying it controls the rebels. The UN also says Rwanda is backing the M23.
On Monday, Rwandan General Joseph Nzabamwita told the AFP news agency that DR Congo had used T55 tanks and mortar bombs to fire into its territory.
Rwanda's army did not respond to the fire, he said.
Various rebels groups have been active in mineral-rich eastern DR Congo since the end of the war in 2003.
The latest conflict broke out after a mutiny in the army in April, when a group of former rebels formed the M23, also known as the Congolese Revolutionary Army.
About 500,000 people have fled the fighting since then.
The M23 is largely made up of ethnic Tutsis, the same group which dominates the government in Rwanda.
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