DR Congo crisis: M23 rebel leader 'flies to Uganda'
The military commander of the M23 rebels is reported to have joined negotiations to end the fighting in the Democratic Republic of Congo.
Sultani Makenga has flown to the Ugandan capital, Kampala, a rebel spokesman said.
The militia is refusing to end its occupation of the eastern city of Goma, hours before the expiry of a deadline for them to leave.
A regional summit at the weekend told the rebels to leave Goma by Monday.
About 500,000 people have been displaced by the rebellion since it began in April, with the formation of M23 after a mutiny in the army.
The presidents of Uganda, DR Congo, Tanzania and Kenya, together with the Rwandan foreign minister, issued a statement calling on M23 to "stop all war activities and withdraw from Goma" and "stop talk of overthrowing an elected government".
Congolese President Joseph Kabila was also urged to listen to the rebels' grievances.
Rebels have rejected previous calls to leave Goma, the main city in eastern DR Congo.
M23 political leader Jean-Marie Runiga said a withdrawal was possible, but could only result from talks with Mr Kabila.
Rwandan Foreign Minister Louise Mushikiwabo told the BBC's Newsday programme Rwanda was ready to "go out of our way to talk to all parties to make sure, first, that fighting stops".
Ugandan officials have not confirmed that Mr Makenga has flown to Kampala - the UN and US recently imposed a travel ban and assets freeze on him.
The UN has accused Rwanda and Uganda of backing the M23, saying the chain of command culminates with Rwandan Defence Minister James Kabarebe.
Both countries have denied the allegations, but Mrs Mushikiwabo said Rwanda did have influence on both parties.
The rebels said they were not given army posts promised in a 2009 deal to end a previous uprising.
Their exact aims are unclear but they have threatened to attack the capital, Kinshasa, if President Kabila did not open negotiations with them.
US congressman Adam Smith told the BBC that the US, the UN and other Western countries had to do more to broker peace in a region which has been bedevilled by conflict for much of the past 20 years.
He said the M23 were not the group to improve the situation in eastern DR Congo, while Hollywood actor and director Ben Affleck, who founded the advocacy group, the Eastern Congo Initiative, said: "The first goal is peace, a ceasefire and reconciliation".
"That's where we can step in and use the levers that we have both with the UN and Monusco [UN peacekeeping Mission in DR Congo] and the $400m that the US puts into that group... as well as our relationship with [President] Kabila and with the African Union and regional players."
The UN has warned of a growing humanitarian crisis in Congo.
Aid officials said the fighting has made camps for people displaced by earlier conflicts inaccessible, with food and medicines running short.
Some five million people died during the 1997-2003 DR Congo conflict, which drew in several regional countries.