NAIROBI (AFP) - Somalia's Al Qaeda-linked Shebab insurgents on Wednesday celebrated the anniversary of the Sept 11, 2001 attacks with a Twitter eulogy for the "courageous" hijackers.

In a series of posts on Twitter, the Islamists vowed "the mujahideen will continue with their jihad against the West until the world is ruled by one sovereign state, an Islamic state".

"A single attack by the mujahideen shattered US dreams of global domination, tarnished their reputation and severely crippled their economy," the Shebab said in one of a series of posts.

"Today, the spark ignited by those courageous 19 martyrs has grown into a raging inferno that continues to threaten every kafir (infidel) aggressor," said another post.

Another post praised the hijackers as "19 young men armed with a rigid faith and a firm conviction".

"History shall remember this day as the day America was subdued, with both its prestige and pride irreparably dented. It's an Islamic revival," the group said.

The Shebab, who are fighting the internationally-backed government in Mogadishu, announced their return to Twitter earlier this week under the new account name @HSM-Press.

Their previous account was suspended last week - the second time they have been pushed off the site this year - after they threatened to kill Somalia's President Hassan Sheikh Mohamud.

Twitter warns that accounts can be suspended if users publish "direct, specific threats of violence against others".