Security agencies on Friday issued a nationwide terror alert and warned that 12 known and suspected al Shabaab terrorists may be planning attacks.

Police issued 11 photos of the most wanted men, considered armed and dangerous, and asked the public for information.

A photo of the twelfth man was not available.

 The men are said to have planned Kenya terrorist attacks, including the Mpeketoni massacre that claimed 60 lives in June last year.

Police have had them on a watch list for more than a year.

"Kenya’s security agents have issued a terror alert following intelligence reports of the 11 listed terrorists possibly carrying out an attack during the festive period” an intelligence report seen by the Star said.

The men are "armed and dangerous” and may have sneaked back into Kenya from al Shabaab camps in Somalia.

They are: Abdifatah Abubakar Abdi, alias Musa Muhajir, a man of Somali descent who lived in Mombasa before deportation to Somalia; Abdifatah Abubakar Abdi; Abdalla Muumin Abdalla; Suleiman Mohamed Awadh; Abdalla Siraj Marum; Mohamed Ali Ahmed; and Hussein Said Omar, alias Babli, the younger brother of fugitive Ahmed Said Omar, alias Dogo.

This group is wanted for their role in the Mpeketoni attack. Others are Issa Abdalla Ahmed, alias Kauni, and Abdikadir Abubakar Abdikadir.

They were reported missing by their families in Malindi in November last year and are believed to have joined the militants.

Kauni, 24, was a driver for six months before he fled to Somalia. He attended Sir Ali bin Salim primary school in Malindi and Malindi Progressive Secondary School.

Abdikadir is a brother of Khadijah Abubakar Abdikar, one of the three young women charged with attempting to join al Shabaab. They were intercepted in Elwak on their way to Somalia in March.

Also listed are Anwar Yogan Mwok and Omar Patroba Juma, alias Patroba Juma Owiti, both wanted involvement in a foiled attack on a KDF base in Buare in June this year.

Mwok, 35, was born in Siaya, raised a Christian, converted to Islam and joined al Shabaab in 2013. He played for Mathare United Football Club.

Ismael Mohammed Shosi (no photo), alias Ismael Mmanga, hails from Malindi but was raised in Mombasa. He is wanted for assassinations and armed robberies.

He is linked to the murder of moderate Sheikh Mohammed Idris, the CIPK Mombasa branch chairman, and the killing of CID officer Mohamed Ibrahim on March 15.

His associates are Mahir Khalid Riziki, Hamisi Mwacheta aka Rasta alias Bilal and Abubaka Majani.