Somalia's Islamist militia have taken control of a key road junction south of their Mogadishu stronghold despite last week's ceasefire.
The Islamic courts control much of southern Somalia
Five people died in the battle for the road that links the capital to the interim government's base in Baidoa.
Meanwhile in Islamist-controlled Jowhar three men face death by stoning if convicted of rape by an Islamic court.
The charges come a day after the new Islamist leader said he would only back a government based on Islamic law.
Sheikh Hassan Dahir Aweys' Somali Supreme Islamic Courts Council is due to hold talks with the weak interim government next month.
Interim President Abdullahi Yusuf strongly opposes political Islam.
The two groups last week agreed not to fight each other, amid fears of renewed conflict in Somalia, which has not had an effective national government for 15 years.
Death by stoning is considered the most severe of punishments under Islamic law, handed down to adulterers and rapists.
Eye for an eye: murder punished by death, for example
Theft: limb amputation
Adultery: death by stoning, if married
Adultery: 100 lashes, if single
Rape: death by stoning
The BBC's Hassan Barise says if the stonings go ahead in Jowhar it is probably only the second incidence of this Sharia punishment in more than a decade of Islamic court justice in Somalia.
In the capital, there have been more than 16 amputations - the punishment for theft - in that time, he says.
Islamic law is based on an eye for eye system of justice. Last month an Islamic court ordered a teenage boy to stab his father's killer to death in public.
Mr Aweys has called on the new Somali government to impose Sharia law but our correspondent says his colleagues have offered assurances they do not want a Taleban-style state.
Named as the head of the Islamic courts' new legislative council on Sunday, Mr Aweys is seen as a hardliner compared to the more moderate Sheikh Sharif Sheikh Ahmed, who recently seized power from an alliance of Mogadishu warlords.
"Somalia is a Muslim nation and its people are also Muslim, 100% - therefore any government we agree on would be based on the holy Koran and the teachings of our Prophet Muhammad," Mr Aweys told the AP news agency.
His predecessor Mr Ahmed is now head of a new executive committee but is thought to be less powerful.
Some correspondents speak of a power struggle between the two factions as Mr Ahmed has said the group does not want political power.
Meanwhile, the United States has said it will not deal with Mr Aweys because of alleged ties to al-Qaeda, a charge he denies.
He used to lead al-Itihaad al-Islamiya, a group which the US described as "terrorist".
The US has said it is willing to work with other leaders allied to Mr Aweys, but it fears that a Somalia run by Islamists could be used by international Islamic fighters.
US State Department spokesman Sean McCormack said the US would be troubled if Mr Aweys' promotion was an indication of the direction the Somali Supreme Islamic Courts Council was heading in.
But Mr Aweys told the AFP news agency he had never killed anybody.
"I am not a terrorist. But if strictly following my religion and love for Islam makes me a terrorist, then I will accept the designation."
President Yusuf defeated al-Itihaad in the 1990s, chasing it out of the northern region of Puntland, which he used to head.
The US is widely believed to have backed the defeated Mogadishu warlords, as part of its war on terror.
It has neither confirmed nor denied the reports but says it will support those working to prevent "terrorists" from setting up in Somalia.