Who are al-Shabaab?

Al-Shabaab is a Somali insurgent group which started as the youth military wing of the Islamic Courts Union (ICU), a group that controlled southern and central Somalia prior to the start of the war in the country in 2006.

The ICU lost power to a transitional government backed by Ethiopia during the war, driving many of the insurgents underground and leading to the creation of Al-Shabaab in late 2006.

The group's main objectives include the instatement of Sharia law in Somalia, as well as waging 'jihad' on targets they deem to be 'enemies of Islam'.

The United States added al-Shabaab to its list of foreign terrorist organisations in February 2008, after claiming the group had links with al-Qaeda.

"Al-Shabab is a violent and brutal extremist group with a number of officials affiliated to al-Qaeda," the US State Department said in a statement at the time.

Experts say al-Shabaab fighters trained with al-Qaeda in Afghanistan, and broadcasts from al-Shabaab have been released on the internet pledging allegiance to Osama bin Laden.

It is alleged al-Shabaab is helping to fund Somali piracy.