The US has extended its designation of the al-Shabab jihadist group as a Foreign Terrorist Organisation to include a Kenya-based wing of the group known as al-Hijra.

Washington says al-Hijra is interconnected with al-Shabab and consists mainly of Kenyan and Somali members.

The move comes at the end of a legally required five-year review of al-Shabab’s status as a terror group.

With these terror designations, the US says it aims to expose and isolate individuals or organisations it considers a threat – and to deny them access to its financial system.

The Somali group al-Shabab has had this label since 2008, the same year al-Hijra was formed in neighbouring Kenya. The State Department says this wing has been openly recruiting for al-Shabab in Kenya and facilitating travel for its members to Somalia "for terrorism purposes".

Security analysts suggest that al-Hijra was involved in planning the siege on Kenya’s Westgate shopping mall in 2013.

A United Nations report named Aboud Rogo – a radical Kenyan cleric – as al-Hijra’s ideological leader.

Rogo was killed in 2012 but continues to inspire Swahili-speaking jihadists in eastern Africa.