Shebab militants killed at least 14 workers in northern Kenya on Tuesday, officials said, the latest in a wave of attacks in the east African nation by the Somali-led Islamists.

The attack occurred just outside the town of Mandera in Kenya’s far northeastern region, which borders Ethiopia and war-torn Somalia, and comes a little more than two weeks before US President Barack Obama is due to make his first presidential visit to Kenya, where his father was born.

"People were sleeping when the attack happened. They just came and hurled explosives into the houses,” said Mandera County Commissioner Alex Ole Nkoyo, confirming 14 people had been killed in the attack.

"These were Al-Shebab from the nature of the attack. They used explosives and guns,” he said.

A pro-Shebab website, Somalimemo, said the Al-Qaeda-affiliated rebels had confirmed they carried out the attack against "Christian Kenyans”.

A regional commissioner, Mohamud Saleh, said the attackers were believed to be Shebab members based in Kenya’s northeast, which has seen a string of attacks in recent months.

"We believe the assailants are members of al-Shebab terror group who are operating from sleeper cells in Mandera town,” Saleh told reporters in Garissa, where in April the Shebab massacred 148 people at the town’s university, most of them students.

He said up to 150 people were targeted in the attack and praised the security forces for responding quickly.

Christian workers targeted

"Our security officers have done a commendable job by rescuing 136 people from the hands of the bloodthirsty terror gangs,” he said, adding any loss of life was "painful”.

Interior Minister Joseph Nkaissery, however, said the attackers had "sneaked into the country” from Somalia and had then "run back to Somalia”. He added that 130 residents were evacuated from the area.

"We are still undertaking a security operation in the area,” he told reporters.

The target of the attack was a guarded compound that is home to labourers who work in nearby quarries. Many labourers who work in the Muslim-majority border region are Christians from central Kenya.

Kenya’s National Disaster Operation Centre said 13 of the dead were "non-locals” and one was from the area. It said five of the wounded had been airlifted to Nairobi for treatment.

Under pressure in Somalia, where it has for years been fighting to overthrow the internationally-backed government, Shebab is now increasingly targeting Kenya. It has also stepped up attacks during the Muslim fasting month of Ramadan.

In late 2014, 28 passengers were dragged from a bus near Mandera and executed.