The call was issued on the Muntadaa website, whose followers support al-Qaeda, and appear to draw mainly from British residents.
"The Ethiopians with full international support (from the Christian crusader regimes) and directly backed by illegitimate Israel (Zionists) have violated the blood of the Muslims in Somalia. By committing such an act of terrorism the Muslims in Somalia and nearby lands have responded to the divine call of Jihad," the message said, posted by a user of the site.
"The obligation of supporting the Jihad all over the world (including Somalia) is Fard Ayn (an individual obligation)," the message continued.
"You can fulfill this duty financially, physically and verbally. This honourable act must be carried out according to your own capabilities because our beloved Prophet Muhammad (saw) said Strike the Mushrik (hypocrite) with your wealth, hands and tongue. Therefore no Muslim (man or woman) has an excuse of doing nothing at all," the statement added.
Quoting a hadith – oral tradition of Islam's prophet, Muhammad - the statement concluded: "Muhammad (saw) said There will always exist a group from my Ummah (nation) who will continue to fight for the Deen (rule) of Allah, always dominating over their enemy… (the group will exist at all times and will always be fighting for the truth until the final hour is established)."
The Muntadaa website is part of a network of UK extremists, currently known as 'The Followers of Ahl Us-Sunnah Wal Jamma' who have sent British volunteers to participate in conflicts in the Middle East, Afghanistan, and Chechnya.