The Union of the Islamic Courts (UIC), a militia which controls the capital and much of the south, has vowed to drive out Ethiopian troops.

The Ethiopians moved into Somalia last Thursday and have been seen in Baidoa, where the beleaguered interim government is based.

Eyewitnesses quoted by the Associated Press news agency say Ethiopian soldiers seized the airport at Waajid, about 70km to the north, before dawn yesterday. The town had been controlled by a local militia. It is unclear whether there was any fighting.

Other residents told Somali media that they had seen Ethiopian soldiers in the town centre.

The UIC has pledged to wage a "holy war" to drive out Ethiopian troops. The Islamic militia drove the warlords from the capital, Mogadishu in June, saying they wanted to restore law and order.

The UIC has since consolidated its power over many parts of southern Somalia.

But Ethiopia is strongly opposed to the militia and has repeatedly warned that it will send its army into Somalia if the government is attacked.

Ethiopia has been a long-term ally of President Abdullahi Yusuf.

UIC leader Sheikh Hassan Dahir Aweys has accused him of being "a servant of Ethiopia".