Failed bus attack in Kenya 'linked to IS faction of al-Shabab'
Kenya's police chief, Joseph Boinnet, has said al-Shabab militants behind this week's thwarted bus attack were linked to the Islamic State (IS) group.
Mr Boinnet said al-Shabab, the Somalia-based Islamist group, had split in two - one faction remaining loyal to al-Qaeda and the other to IS.
On Monday, Muslims protected fellow Christian passengers when their bus was ambushed near the Somali border.
In April 148 people died in a single al-Shabab attack in Kenya.
The actions of the passengers on the bus on its way from the capital, Nairobi, to Mandera, were widely hailed, with one local politician saying it showed "a sense of patriotism and belonging to each other".
The police chief, giving his new year message, urged Kenyans to remain vigilant as he said that there were about 100 al-Shabab fighters operating in the north-east of the country, Kenya's Standard newspaper reports.
"Shopping malls, entertainment spots, restaurants and places of worship... are potential soft targets," he is quoted as saying.
Al-Shabab is currently battling to keep the loyalty of its fighters as IS tries to gain a foothold in East Africa, the BBC's Africa security correspondent Tomi Oladipo reports.
It has historically been connected to al-Qaeda but in October Sheikh Abdulqadir Mumi, a prominent former "spiritual leader" and recruiter for al-Shabab, declared allegiance to IS. It is not clear how many followers he has taken with him.
Mr Boinnet is the first Kenyan official to talk about the split in al-Shabab.
IS currently controls parts of Syria and Iraq but also has a foothold in Libya.
The Nigeria Islamist group Boko Haram pledged allegiance to IS earlier this year.
Al-Shabab attacks in Kenya
September 2013 - Al-Shabab militants seize the Westgate shopping mall in the capital Nairobi, killing 67 people.
June 2014 - At least 48 people die after Islamist militants attack hotels and a police station in Mpeketoni, near the island resort of Lamu.
November 2014 - The group targets a bus full of teachers in Mandera County, executing 28 non-Muslims at point-blank range.
December 2014- Al-Shabab kills 36 non-Muslim quarry workers near the north Kenyan town of Mandera.
April 2015 - Militants carry out a massacre at Garissa University College in north-east Kenya, killing 148 people.
December 2015 - Bus attack in Mandera thwarted.