Kampala - Ugandan President Yoweri Museveni on Friday dismissed threats by Somali insurgents to attack his country, which provides troops to the African Union peacekeeping force in Somalia.

"We know how to attack those who attack us," he told reporters at the end of an AU summit in Kampala. "They should concentrate on solving their problems instead of thinking of attacking Uganda."

A Somali insurgent commander on Thursday called on his fighters to attack the capitals of Uganda and Burundi, which also provides troops to the peacekeeping mission, following a battle in which at least 20 civilians died.

The fighting broke when the insurgents, who have been pushing to oust the Western-backed government, attacked President Sheikh Sharif Sheikh Ahmed as he flew to Kampala to attend the AU conference on internally displaced people and refugees.

The AU peacekeeping mission AMISOM returned mortar fire toward a popular market and residential areas, killing at least 20 civilians and injuring over 60, witnesses and medics said.

AMISOM - the target of a recent suicide bombing that killed 17 peacekeepers - is propping up the government in Somalia, which has been embroiled in chaos since the
1991 ouster of dictator Mohamed Siad Barre.

The insurgency, which kicked off in early 2007 following an Ethiopian invasion, has recently gathered pace.

Islamist insurgent group al-Shabaab and its allies Hizbul Islam in May launched a renewed push to oust Sheik Sharif, a former insurgent ally who came to power early this year as part of a United Nations- backed peace process.

More than 250,000 people fled daily heavy battles, which trailed off after a few months.

There had been little violence in Mogadishu in recent weeks as al- Shabaab and Hizbul Islam turned on each other in a power struggle over control of the port town of Kismayo.(dpa)