Somalia's encircled interim government said on Monday it had closed all land, air and sea borders.
The government is encircled by Islamist fighters in its south-central provincial base Baidoa and has no control over its borders.
"The government has decided to close our borders, air space and sea space," government spokesman Abdirahman Dinari said by telephone.
"We are requesting the international community, especially neighbouring states, to help us effect this."
The government is defended by neighbouring Ethiopia, which on Sunday began launching air strikes against the Islamists.
Ethiopian Prime Minister Meles Zenawi says he is waging war against the religious movement to protect his nation's sovereignty, intensifying a conflict that threatens to engulf the Horn of Africa.
Officials and residents said Ethiopian jets attacked Mogadishu International Airport on Monday, wounding at least one person.