Somalia militia al-Shabaab has threatened revenge attacks against Kenya if the government does not withdraw its troops from the war-torn country.
In a statement, the Al Qaeda linked group also denied involvement in the kidnapping of foreign tourists and aid workers dismissing the "allegations put forward by the Kenyan authorities with regard to the recent kidnappings are, at best, unfounded".
Al-Shabaab said Tuesday that the lives of thousands of Kenyans will be in danger its government continues with military operation inside Somalia.
"The Kenyan public must understand that the impetuous decision by their troops to cross the border into Somalia will not be without severe repercussions.
"The bloody battles that will ensue as a result of this incursion will most likely disrupt the social equilibrium and imperil the lives of hundreds of thousands of civilians; and with war consequently comes a significant loss of lives, instability, destruction to the local economy and a critical lack of security," the militia group said.
The terror network urged the Kenyan public to think of their safety.
"We have experienced decades of war and instability in our country and fully understand the costs and the consequences of the conflicts. Do not let the flames of this war spill over into your country, thereby destroying the notion of safety and stability that you have enjoyed for years.
"Do not entrust your fate and the fate of your country to a few sabre-rattling politicians. It is your government and the choice is in your hands."
On Sunday, Kenyan forces were operating deep inside Somalia with orders to make sure there are no al Shabaab extremists within 100 kilometres of the border.
Units from the Kenya Army are understood to have crossed into Somalia at Liboi and Mandera with orders to fight their way into the lawless country and create a buffer zone to ensure that insurgents do not launch attacks against Kenya.
Kenya Air Force and the Navy will be sent out as the need arises, security sources told the Nation.
Soldiers actually crossed into Somalia days before the announcement by Internal Security Minister George Saitoti and Defence Minister Yusuf Haji. (READ: Kenya declares war on Al Shabaab)
Internal Security permanent secretary Francis Kimemia said security forces had drawn up strategies to defeat al Shabaab in their own land.
“How it will be done, the number of troops involved and where they will strike remains a preserve of the military. We can’t give information that would be useful to the enemy,” he said.
Witnesses have reported military trucks at border points and military choppers in the air. Foreign troops are already on the ground in Somalia, mainly from Uganda and Burundi, under the African Union.
Last week, two Spanish aid workers were kidnapped at the Daadab refugee camp. (READ: Two Spaniards kidnapped in Kenya likely in Somalia)
French woman Marie Dedieu was kidnapped on Manda Island on October 1 while Mrs Judith Tebbutt a Briton, was abducted and her husband David shot dead at Kiwayu resort in Kiunga in September.
However, al Shabaab denied they were behind the two incidents.
"Harakat Al-Shabaab Al Mujahideen hereby categorically denies all charges pertaining to the kidnapping of tourists and aid workers from inside Kenya.
"The allegations put forward by the Kenyan authorities with regard to the recent kidnappings are, at best, unfounded and, apart from the mere conjectural corroborations, not substantiated with any verifiable evidence."