Thousands of Sri Lankan civilians are fleeing homes in the east after fighting between Tamil Tiger factions, the Red Cross has said.
Col Karuna's troops on the retreat from the Verugal river
Clashes erupted early on Friday between breakaway commander Colonel Karuna and the mainstream Tiger faction around the Verugal river.
Col Karuna's forces have now retreated south from their frontline positions.
The area was reported quiet on Saturday morning, with a military spokesman saying rebel forces had withdrawn.
The fighting is the first between the two factions since the colonel broke away from the main Tamil Tiger structure at the start of last month.
The BBC's Anna Horsburgh-Porter in Colombo says it is still too early to tell whether the northern Tamil Tigers will push down further to reclaim their eastern headquarters, now that Colonel Karuna has pulled back.
De facto border
At least nine fighters are thought to have been killed and another nine people injured.
The casualty figures come from rebel sources but relate only to the south of the area affected, not to the north, so the figures may be higher.
The Red Cross said supplies were being sent to the area to help people fleeing villages.
Thierry Meyrat, head of the International Committee of the Red Cross in Colombo, told Asia Today on BBC World: "We have figures of some 3,000 people who have gone from the areas of fighting and are being taken care of tonight in schools where they will receive meals.
"It's possible that more people will be displaced."
Fighting is thought to have taken place close to the coast.
Verugal river has been the frontline since Col Karuna's breakaway
S Kumar, a senior commander of Col Karuna's faction, told the Associated Press news agency: "About 1,000 people came and attacked us, so this is a tactical withdrawal and we are going to set up our new defence line."
Regional officials said fighters fired mortars and small arms fire for nearly two hours early on Friday across the river.
A spokesman for the international monitors of a two-year ceasefire between the government and Tiger rebels said the northern faction had captured a small coastal base at Kathiraveli, some way into territory controlled by Col Karuna.
The rebel organisation split last month after Col Karuna broke away saying he wanted to form his own administration.
The mainstream Tigers have denounced him as a traitor and threatened to kill him.
The TamilNet website, which is close to the main faction in the north, said that during the clashes more than 300 young cadres of the Karuna faction had surrendered without a fight.
That sparked concern at the United Nations Children's Fund, Unicef, which said any underage fighters should immediately be released into its care.