Somalia's Islamic Courts militia has seized a key town outside the capital, Mogadishu, from a member of the warlord alliance it is fighting.
Balad, 30km (19 miles) north of Mogadishu, lies on the main road to Somalia's most fertile regions.
It was controlled by warlord Muse Sudi Yalahow, who is officially trade minister in the transitional government set up to bring peace to Somalia.
The latest Islamist victory comes after they had seized much of the capital.
The warlords have controlled Mogadishu since they toppled Somalia's last effective government 15 years ago.
This year's clashes have been the most serious for more than a decade, with some 330 people killed in the past month.
At least 15 people were killed in the fight for Balad, local residents said.
Mr Yalahow's gunmen fled towards the town of Jowhar, they said.
Meanwhile, another member of the warlords' Anti-Terror Alliance, Mohamed Qanyare Afrah, is reported to have left his base in the Dayniile district of Mogadishu, with a dozen battlewagons, known as "technicals".
He had planned to help in the battle for Balad but has now moved on to Jowhar, reports the BBC's Mohamed Olad Hassan in Mogadishu.
On Saturday, UN aid workers pulled out of Jowhar in case the fighting spread there.
After seizing Balad, on the road from Mogadishu to the Lower and Middle Shabelle regions, Islamic Courts leader Sharif Sheikh Ahmed called on the warlords to stop fighting and take part in a dialogue to unify the Somali people.
He also urged them to vacate a hospital they seized last week - which the United Nations condemned as a violation of international law.
The Islamic Courts has long said the warlords in the Anti-Terror Alliance were being backed by the United States.
The US merely says it will support those trying to stop people it considers terrorists setting up in Somalia but stresses its commitment to the country's transitional government, which functions from Baidoa, 250km (155 miles) north-west of the capital.
On Friday, thousands of people held an anti-US demonstration in Mogadishu
"Down with the unbelievers and down with the dollar receivers," read one banner.
But on Sunday, Mr Ahmed struck a conciliatory note.
"We are telling the international community that we are not against anyone, and we will treat everyone the way they treat us. We'd like to concentrate on our own affairs and we don't want to harm anyone," he said.
The violence began earlier this year when a group of warlords, who had divided Mogadishu into fiefdoms, united to form the Anti-Terrorism Alliance to tackle the Islamic Courts, who they accused of sheltering foreign al-Qaeda militants.
The Islamic Courts deny this. They were originally set up in Mogadishu by businessmen to establish some law and order in a city without any judicial system.
The Anti-Terrorism Alliance includes eight warlords, four of whom are ministers in the government, which only controls a small part of the country.
President Abdullahi Yusuf has urged the US to channel its campaign against Somalia's Islamists through his government, rather than the warlords.
He has come under pressure from some MPs to sack the warlords because of the fighting in Mogadishu.