NAIROBI, Dec 25 (Reuters) - Somalia's encircled interim government said on Monday it had closed all land, air and sea 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 interim government is encircled by Islamist fighters in its south-central provincial base Baidoa. Its Ethiopian allies have launched air strikes against the Islamists.