Six police personnel in north-east Kenya have been killed after assailants attacked a base near the border with Somalia, a regional official said.

No group has claimed responsibility, but Garissa County Commissioner Mohamed Mwabudzo told the BBC the style of the attack followed a pattern of raids by Somali-based Islamist militant group al-Shabab.

He said the officers were ambushed on Sunday at 05:30 local time (02:30 GMT), while they were preparing for their morning prayers.

In addition to the six officers who died, four officers were taken to hospital with injuries.

Al-Shabab frequently mounts cross-border attacks in the area, targeting both the Kenyan military and civilian populations.

Mr Mwabudzo said the "guerrilla-style" nature of the attack aligns with al-Shabab's "pattern of cross-border raids aimed at destabilising the region".

"The suspected militia used assorted weapons to overrun the camp," he added.

The camp targeted in the assault was housing reservists - local volunteers who assist the regular police in securing remote areas.

Al-Shabab - affiliated to al-Qaeda - controls large parts of southern and central Somalia.

The group has waged a brutal insurgency against Somalia's government for nearly 20 years.