Somalia's Islamists on Tuesday dismissed as illegitimate the vote which saw outsider Hassan Sheikh Mohamoud elected president.
"The process in which Hassan Sheikh Mohamoud was chosen was run by the enemies of Somalia," Sheikh Ali Mohamoud Rage, spokesman of the al-Qaida-linked Shebab, told Agence France Presse.
"Nothing personal, but the whole process is like an enemy project," he said.
Hassan Sheikh Mohamoud, a 56-year-old university lecturer with ties to the Somali branch of the Muslim Brotherhood, Al-Islah ("Reform" in Arabic), unexpectedly defeated incumbent Sharif Sheikh Ahmed in a run-off on Monday.
The president was elected by newly-designated lawmakers as part of a U.N.-backed process to end a transitional period and strengthen institutions in a nation which has not had an effective central government in two decades.
The vote took place under tight security in the capital Mogadishu and comes amid intensifying regional military efforts to flush out the Shebab from their remaining strongholds.
"We will only recognize a process run by Somalis and not manipulated by Ethiopia, Burundi, Kenya, Uganda, Djibouti and the west," Rage said, listing the countries that have troops fighting the Shebab in Somalia.
"Hassan is operating under a constitution drafted by the enemies of Somalia, who have a nefarious geopolitical agenda, especially neighboring countries," he said.
Outgoing president Sharif Sheikh Ahmed was a top leader in the Islamist movement that gave birth to the Shebab until he joined the U.N.-brokered political process and won the presidential vote in January 2009.
The Shebab have since accused him of being a Western puppet supporting the country's invasion by "Christian crusaders" and have repeatedly targeted his administration in suicide attacks.