Al-Qaida's Yemen affiliate claimed responsibility for the murder of an award-winning journalist turned top official of the Shiite Huthi militia, the group said on Thursday on Twitter.

The claim was made by Ansar al-Sharia, or Partisans of Sharia (Islamic law), which is linked to the Sunni extremist al-Qaida in the Arabian Peninsula (AQAP).

A brief statement on Twitter said two militants of the group riding motorcycles opened fire on Abdul Karim al-Khiwani on Wednesday near his home in the centre of Sanaa, before fleeing.

Khiwani was a member of the Revolutionary Committee of the Huthis that control Sanaa and had been head of the militia's media department.

In 2008 he was awarded the Amnesty International Special Award for Human Rights Journalism under threat.

Amnesty has denounced the "despicable killing of a leading journalist and activist," saying Khiwani had a history of being harassed for his "outspoken journalism and peaceful activism", and called for a probe.

The United States considers the Yemen-based AQAP the most dangerous branch of the global jihadist network.