Security, service delivery and economic activity in northeastern Kenya have deteriorated since October 2011, when the country’s military forces deployed in neighbouring Somalia in an effort to eradicate the Al-Shabab militia, which has vowed to avenge the incursion.

In December alone, at least 15 incidents involving grenades or improvised explosive devices (IEDs) occurred in the regions of Garissa, Wajir, Mandera and Dadaab, where some 463,000 people, mostly Somalis, are housed in the world’s largest refugee complex. In the latest incident on 11 January, at least two police officers and four civilians were killed in a raid at the Gerrile border post in Wajir area; other government officials were reported missing, presumably abducted.

Al-Shabab said on its Twitter account that it carried out this attack. Several blogs reportedly associated with the group also said one of its units was responsible for killing a refugee leader in Dadaab in December because he helped the authorities to locate IEDs there.

Confirming the Gerrile incident, the regional commissioner Wenslas Ongayo said an operation was under way to rescue the missing officials.

One local government official in the northeast, who asked not to be identified, told the UN news agency IRIN the insecurity had restricted his duties.

“I am supposed to travel to some areas very close to the Somali border,” he said. “But my life is important to me and my family and I no longer make any field trips since the Al-Shabab killed three government workers [there] two months ago.”

An aid worker in Mandera, on the Somali border, said thousands of hungry families who relied on food aid had been affected by the withdrawal of relief agencies.

“How can NGOs believe repeated pledges by the government that it will protect them, whereas almost a dozen of our officers in the police and army have been killed in attacks staged by Al-Shabab in Mandera this year alone?” asked the aid worker.

The police commander in Northeastern Province, Leo Nyongesa, said security measures had been stepped up.

“We are doing a lot; our forces have arrested many Al-Shabab fighters and agents and foiled a number of attacks,” Nyongesa told IRIN.

Nyongesa added that the spate of grenade attacks against security personnel would not deter Kenyan security forces in their quest to fight “terrorism”. Hussein Omar, a local government official in Ijara, which also borders Somalia, said the council had lost revenue because the livestock trade had come to a stop in this largely pastoralist area.

In addition, Kenyan authorities and foreign governments have warned of heightened threat of attack in the capital, Nairobi. In a travel warning, the British government said: “We believe that terrorists may be in the final stages of planning attacks. Attacks could target Kenyan institutions as well as places where expatriates and foreign travellers gather, such as hotels, shopping centres and beaches.”