Kenya bus attack: Al-Shabab 'wants religious war'
The slaughter of 28 people on a bus in Kenya is a bid to start a religious war, a senior adviser to President Uhuru Kenyatta has told the BBC.
Abdikadir Mohammed called on Kenyans of "all faiths and creeds" to stand together against the "heinous crimes".
At dawn on Saturday, al-Shabab gunmen attacked the bus in northern Kenya, shooting dead non-Muslim passengers.
The Somalia-based Islamist group has carried out numerous attacks across Kenya since 2011.
The bus was travelling to the capital, Nairobi, when it was stopped in Mandera county, not far from the border with Somalia.
Gunmen separated out non-Muslims by asking passengers to read from the Koran, officials and witnesses said. Those who failed were then shot in the head.
Kenya's Red Cross confirmed that 28 of the 60 passengers on the bus were killed, 19 men and nine women.
One survivor, Douglas Ochwodho, told how he was singled out to be killed but was not shot and then pretended to be dead among the bodies.
"The aim is to create conflict between the Muslims and the non-Muslims in this country," Mr Mohammed told the BBC. "The aim is to create a religious war, religious strife, in Kenya."
"We have had a lot of the Muslim leaders come out today [Saturday] and strongly condemn this and call on Kenyans of all faiths and creeds to stand together against these heinous crimes and criminals."
Al-Shabab said the attack was in retaliation for recent killings of Muslims by the Kenyan security forces in the coastal town of Mombasa.
The Kenyan authorities said they had begun to identify the killers and would bring them to justice.
The interior ministry said a camp belonging to the attackers had been destroyed by Kenyan military helicopters and jets, with "many killed".
Analysis: Anne Soy, BBC News, Nairobi
Mandera shares a long and porous border with Somalia. The area - in fact the region - has been prone to insecurity since Kenya's independence in 1963.
It's a vast arid and semi-arid area that is sparsely populated and characterised by poor infrastructure and very few schools and hospitals. Communities in the north have felt marginalised by the national government for decades.
Guns are readily available due to its proximity to Somalia and the south of Ethiopia where the Oromo Liberation Front is active. Al-Shabab has a base on the Somali side of the border - Gadondhawe - which was recently bombarded by Kenyan warplanes.
It's a confluence of factors that makes it a fertile ground for recruitment by the militant group.
One of the passengers on the bus told the BBC that the bus driver tried to accelerate away from the militants but the vehicle became stuck in mud, about 30km (19 miles) from Mandera town.
He said about 10 heavily-armed men speaking Somali ordered the passengers off the bus.
"When we got down, passengers were separated according to Somali and non-Somalis," the passenger said.
Some Somalis were shot after pleading with the gunmen to spare non-Somali passengers, he said.
A local official quoted by Kenyan media said the government had failed to answer their pleas for extra security in an area "prone to attacks".
"This is not the first time the government has totally ignored us, and you can now see the how many innocent precious lives have been lost," county official Abdullahi Abdirahman said.
"Today we are experiencing avoidable massacre," he added.
Britain and the United States condemned the attack, pledging to help Kenya in its fight against terrorism.
Last week, Kenyan police shut down four mosques in the port city of Mombasa, a largely Muslim city, saying they were being used to store weapons. The raids triggered apparent revenge attacks by Muslim youths.
Kenya has experienced a series of al-Shabab attacks since it sent troops to Somalia three years ago to help fight the militant group.