Heavy fighting has again flared in the Somali capital, Mogadishu, after 10 people were killed on Saturday.
Mogadishu is controlled by thousands of gunmen
A BBC correspondent in the city says at least five people have died after rocket-propelled grenades and anti-aircraft guns were fired.
The fighting pits a new group, the Alliance for the Restoration of Peace and Counter-Terrorism, against the Islamic Courts' militia.
Peace talks are due next week, aimed at restoring authority after 15 years.
Most of those killed and wounded over the weekend were civilians hit by stray bullets, says the BBC's Hassan Barise in Mogadishu.
Hundreds of families have fled their homes around the former military academy following the heaviest fighting in Mogadishu for several years.
Over the weekend, a group of MPs urged both sides to stop fighting.
"We remind the warring sides that no-one ever won a war during the past 15 years of fighting," said a statement read out by Culture Minister Abdi Hashi Abdullahi.
Our correspondent says at least five warlords-cum-ministers in the transitional government are behind the new alliance, which is battling the Islamic Courts.
The courts have set up Mogadishu's only judicial system in parts of the capital but have been accused of links to al-Qaeda.
Their critics accuse the courts of being behind the killing of moderate Muslim scholars.
Our correspondent says the latest fighting is not linked to the first meeting in Somalia of the transitional parliament since it was chosen in August 2004.
The MPs have been divided over whether Mogadishu is safe enough to host the new government.
Mr Yusuf and his supporters say it is too dangerous and has been based in Jowhar, while others, led by Parliament Speaker Sharif Hassan Sheikh Adan, insist that the president does not have the authority to change Somalia's capital.
The meeting is to be held on 26 February in the town of Baidoa - seen as a compromise between the two factions.
There has been no effective central government in Somalia since 1991 and rival warlords have divided the country between them.