Thirteen Kenyan police are missing following an overnight ambush by suspected Shebab militants in the northeast of the country close to the border with Somalia, a police spokesman said Tuesday.

Local officials said more than 10 officers may have been killed in Monday night's ambush near Garissa -- the scene of last month's university massacre -- while Kenyan media reported the number of dead could be as high as 20.

"There was an ambush on officers who were on patrol and as a result, 13 officers are missing," police spokesman George Kinoti said. "Two others sustained injuries and have been taken to hospital."

"More police officers have been dispatched to look for those missing and the attackers," he said.

The attack in Garissa county came just days after extra Kenyan security forces were deployed in the area to strengthen security after a series of raids by gunmen from the Somali-led Al-Qaeda branch.

The officers were ambushed as they went to assist other police who had been targeted by an explosive device, believed to be a landmine or roadside bomb.

"The area is on the remote side of Garissa not far from the border, that is why we are having a problem getting information instantly," said a police officer based at the county headquarters. "What we however know is that several officers have been killed."

Garissa County has remained volatile with numerous attacks since last month when four Shebab militants stormed Garissa University College, killing 142 students and 6 security forces during a day-long siege.

Security sources said the officers were attacked close to the village of Yumbis, about 80 kilometres (50 miles) northeast of Garissa and the scene of a clash between the Shebab and Kenyan security forces last week.

Also last week Shebab militants briefly took control of a mosque in Garissa, delivering a hardline sermon to captive worshippers, before leaving.

Once a Somalia-focussed insurgency Shebab has in recent years turned its attention to Kenya, demanding it withdraw soldiers that were deployed to Somalia in 2011, and launching a series of attacks including the 2013 assault on Nairobi's Westgate mall that killed at least 67 people.