Kenya hunted Shebab militants deep inside Somalia yesterday, claiming self-defence for an unprecedented incursion which the insurgents warned would trigger reprisals in the heart of Nairobi.

Backed by aerial bombings and guided by pro-government Somali forces, Kenyan troops moved deeper into southern Somalia, a day after Nairobi declared war on the Shebab militia and confirmed that it had sent its army across the border.

Kenyan soldiers were reported near the village of Qoqani, some 50 miles inside southern Somalia, a Shebab stronghold.

“The Kenyan troops supported by tanks and other military vehicles have taken up positions near Qoqani,” said Saleban Mohamed, an elder in a nearby village.

“I saw around 32 trucks and tanks, with hundreds of troops,” he added.

“The Kenyan soldiers are heavily armed and they have started digging trenches near Qoqani,” Abdulahi Sayid Adam, another witness said.

The last time one of Somalia’s neighbours unilaterally invaded was in late 2006 when Ethiopia started an occupation that lasted two years and spurred the formation of the Al Qaeda-inspired Shebab insurgency.

The assault came after Kenya’s Internal Security Minister George Saitoti vowed to attack the Shebab “wherever they will be.”

“The Kenya government is taking robust measures to protect and preserve the integrity of the country,” Defence Minister Yusuf Haji said yesterday, dubbing the invasion Operation Linda Nchi — or “Defend our Country.”

In the past five weeks a British woman and a French woman have been abducted from beach resorts in two separate incidents.

On Thursday, two Spanish aid workers were seized by gunmen from Kenya’s crowded Dadaab refugee camp.

“Kenya has peace, its cities have tall buildings and business is booming there, while Somalia is in chaos,” Shebab spokesman Sheikh Ali Mohamud Rage told reporters at a press conference.

“If your government ignores our calls to stop its aggression on Somali soil, we will strike at the heart of your interests,” he said, addressing the Kenyan population.