"Sadc should immediately provide assistance to the armed forces of DRC," Salomao said on Sunday, reading out the summit's communique.
"Sadc will not stand by and witness any destructive acts of violence by any armed groups ... and if necessary will send peacekeeping forces."
He said that a military advisory team would be deployed immediately to provide advice to the DRC's armed forces.
Salomao said the DRC armed forces need to be assisted to protect the country's territorial integrity and sovereignty.
He also said that the region would ask the UN to expand the mandate of its peacekeeping mission, known as Monuc, which is not allowed to engage in active clashes in eastern DR Congo.
But Nkunda on Monday said he was ready to fight regional peacekeepers if they entered the country and supported the Congolese army and its allies.
"If they come in and fight alongside the FARDC and the FDLR, they will be weakened. I am ready to fight them. They will share the same shame as the DRC government, " he told the Reuters news agency by telephone from eastern Congo.
Sadc's pledge to help came as war zones in eastern Congo faced a health crisis.
Outbreaks of cholera have been reported by medical workers in the east of the DR Congo, close to where government forces are fighting to repel an onslaught by Nkunda's rebels.
Half of the 80 cases identified by Medicins Sans Frontieres (MSF) were found in a refugee camp in Kibati, 10km from Goma, the capital of North Kivu province.
Megan Hunter, local emergency programme co-ordinator for MSF, said on Sunday: "There are many displaced people in [the Kibati] zone who live under very bad sanitary conditions. All the risk factors are there for an explosion of a major epidemic."
After a day of relative calm, fresh fighting broke out on Sunday near Goma, Lieutenant-Colonel Jean-Paul Dietrich, the spokesman for the UN mission in Congo, said.
"There have been heavy weapons clashes since 5am (03:00 GMT)" in the town of Ngungu, about 60km west of Goma, he said.
"Thousands of people are arriving at the Monuc base at Ngungu" to take shelter from the fighting, he said.
Hundreds of people are believed to have been killed in fighting between government forces and the rebels.
More than a quarter of a million people have been displaced, the UN says.
On Saturday, the UN said it had evidence that CNDP fighters and pro-government militias have killed civilians in the region.
Alan Doss, the senior UN envoy in DR Congo, said that "war crimes that we cannot tolerate" were committed in the village of Kiwanja, near Goma.
"We condemn them, we deplore them, and we remind the different groups involved that international law is very clear on this," he said.
UN officials said that local fighters, known as Mai Mai, first attacked the villagers on Tuesday.
Fighters from the CNDP then won control of the village and killed those who they thought supported the Mai Mai.
|Thousands have fled the fighting and taken shelter in refugee camps [AFP]
Anneke Van Woudenberg, a researcher with Human Rights Watch, and Dietrich said it appeared the rebels had committed many more killings than the militia.
The killings highlighted the inability of UN peacekeepers to protect civilians.
Monuc has a base in Kiwanja, but it has only 120 soldiers to protect up to 50,000 people.
"We have tried our utmost to portect civilians wherever we can," Doss told Al Jazeera.
"Please remember that this is a huge area. There are 10 million people in Kivu and we have less than 10,000 peacekeepers.
"In many places we are the only presence there to protect people. The situation would have been infinitely worse had we not been there."
Al Jazeera's Mohammed Adow, reporting from Goma, said that the peacekeepers had had little success in protecting civilians.
"The UN has been sending teams to the battle scenes, but they can only stand around and watch as the fighting continues," he said.
The flow of people moving towards already overburdened refugee camps has shown not sign of slowing, Adow reported said.
"People in the camps are living in terrible conditions. There is no shelter left, so people are building shelters out of banana leaves - that is all they have to protect themselves from the rain.
"It has been raining every day for the past nine days. These people do not have clean water and they have nothing to treat the water that they use.
The UN estimates that about 253,000 people have been displaced since September.
The CNDP says it is fighting to protect the rights of ethnic Tutsis in DR Congo, while the country's government has accused neighbouring Rwanda of aiding the rebels.
The Rwanda government denies that it has given any support to the CNDP, calling the crisis a purely Congolese problem.