Mogadishu, Somalia ? Ethiopian forces and Somali government troops fought an intense daylong battle against insurgents Thursday in the Somali capital, leaving at least 15 civilians dead and 30 wounded over the past 48 hours and threatening the safety of U.S.-backed Ugandan peacekeeping troops.

In some of the worst fighting in the past 15 years, Ethiopian forces at the presidential palace and at a military base in the south of Mogadishu fired artillery and mortars at insurgents around the area of the Ramadan hotel, which had been the headquarters of an Islamist government that ruled briefly until Ethiopia overthrew it in December.

The transitional Somali government, which had announced the urban offensive, provided ground forces as well as truck-mounted anti-aircraft and grenade launchers. But it wasn’t clear whether they’d captured more territory from the Hawiye clan, which dominates Mogadishu and had close links with the overthrown Council of Islamic Courts government.

Ethiopian officers met clan leaders Thursday during the fighting in a bid to revive a cease-fire that was reached earlier this month, but the meeting broke up over an Ethiopian demand that all militia commanders take part in the talks, a spokesman for the Hawiye elders said.

The Bush administration had provided military and political support for Ethiopia’s overthrow of the Islamic Courts movement, charging that the Islamists had given sanctuary to al-Qaida fugitives.

The sound of artillery bombardments and machine-gun fire could be heard throughout the capital from 8 a.m. till 5 p.m. The two sides were little more than a mile apart and at times fought house to house.