The armed Somali group al-Shabab has been offering up to $8,000 as a reward for the murder of Kenyan security officers, according to intelligence inputs.
An intelligence message intercepted from the al-Qaeda-linked group reveals fighters being offered the reward for killing Kenyan officials, Maalim Mohammed, Garissa County Commissioner, said on Thursday.
The assassination-for-pay offer by al-Shabab varies with the security officer's rank, Mohammed said.
He said the fighters' communication was intercepted on a VHF radio frequency.
Colonel Cyrus Oguna, the Kenyan military spokesman, said the military knows al-Shabab is offering a reward for the death of Luitenant Colonel Jeff Nyaga, who has been critical in Kenya's successful push against the fighters in southern Somalia.
Oguna confirmed that the fighters were offering $8,000 for Nyaga's death.
Mohamed said local residents were complicit in recent attacks on Kenyan security forces that have caused the deaths of 10 police officers and four soldiers in northeastern Kenya.
"How else would attacker have identified the soldier who was in civilian clothing?" he said.
An army sergeant on vacation and a civilian were shot dead on Sunday in Garissa by gunmen.
'Impact on security'
Al Jazeera's Peter Greste, reporting from Nairobi, said the offer could not be confirmed at the time, however, the Kenyan authorities were convinced that this was a genuine threat from al-Shabab.
"What the Kenyan government has done is that they have canceled all applications for asylum seekers and refugees,
Greste said that human rights activists however, are saying that this is a punitive measure which is unlikely to make a real impact on security.
Garissa is mostly populated by ethnic Somalis, many of whom are Kenyan citizens.
Kenya has experienced a string of gun and grenade attacks since it sent troops last year into Somalia to pursue the al-Shabab fighters.
Three Kenyan soldiers on their way to Somalia were killed last month.
One woman was shot and hundreds of shops were burnt to the ground as the Kenyan army responded to the killings.
Witnesses said Kenyan troops opened fire at random and torched the town's main market.