Kampala  - Uganda and Burundi have put two battalions on standby to send to war-torn Somalia to fill the gap left by withdrawing Ethiopian troops, a Ugandan army spokesman said Friday.

"There is no time framework under which we will send our soldiers there," Major Felix Kulayigye told Deutsche Presse-Agentur dpa. "We have a battalion ready, and it is just a matter of waiting for the logistics and then we will go."

Ethiopia is pulling its forces out of Somalia after a two-year occupation that has failed to defeat Islamist forces.

Ethiopian forces invaded in late 2006 to help kick out the Islamic Courts Union, a hardline Islamist regime that was in power for six months.

The invasion sparked a bloody insurgency that has killed an estimated 16,000 civilians and displaced around 1 million.

Analysts have warned that the departure of Ethiopia's 3,000 troops could lead to more anarchy in the Horn of Africa nation as Islamist insurgents and other militias struggle to seize power.

Others hope that the Ethiopian departure and the resignation of President Abdullahi Yusuf Ahmed can give fresh impetus to a UN-backed peace process.

Somalia has been mired in chaos since the 1991 ouster of dictator Mohamed Siad Barre.

Uganda and Burundi form an African Union (AU) peacekeeping mission of around 3,000 troops.

The AU has been appealing for at least 8,000 extra troops, but only Uganda and Burundi have so far responded.

Other countries, including Nigeria, South Africa and Ghana, have failed to meet their promises to send soldiers.

Ugandan has previously threatened to pull out its forces unless other AU troops were provided to fill the gap left by the Ethiopians.

The conflict, combined with drought and rising food prices, has created a humanitarian catastrophe. Some 3.25 million people in Somalia, almost half the population, are dependent on food aid.

However, the security situation has hampered the delivery of aid.

The United Nations World Food Programme (WFP) warned on Thursday that it might have to stop distributing food in Somalia if the safety of its staff cannot be guaranteed.

Two WFP aid workers were shot in early January, adding to another five killed last year. (dpa)