Ethiopian and Somali government forces have captured a key town in southwestern Somalia from militant group al-Shabab.

Witnesses tell VOA that troops took control of Baidoa without a fight Wednesday, after al-Shabab fighters withdrew from the town.

The town was once the home of Somalia's Transitional Federal Government, until al-Shabab took control of it in 2009.

Ethiopia, Kenya and the African Union all have troops in Somalia helping the government battle the militants. Al-Shabab, which is allied with al-Qaida, has tried to topple the government since 2007 and turn Somalia into a strict Islamic state.

In New York Wednesday, the U.N. Security Council authorized the African Union to increase its force in Somalia to 17,700 troops, an increase of nearly 6,000.

The AU mission in Somalia, known as AMISOM, recently pushed al-Shabab out of the capital, Mogadishu, while Ethiopian troops expelled the militants from the central town of Beledweyne.

The militant group still controls parts of central and southern Somalia but appears to be weakening.

Ethiopian and Somali government troops began driving toward Baidoa on Sunday, and a Somali government official had predicted the town would be “liberated” by Friday prayers.

The capture comes one day before a one-day international conference on Somalia's future in London. Somalia's president and prime minister are due to attend, as is U.S. Secretary of State Hillary Clinton.

The Horn of Africa country has endured two decades of chaos and conflict since the fall of its last stable government in 1991.