NAIROBI, Kenya — Five Kenyan soldiers were killed when a roadside bomb blew up the vehicle they were travelling in the country's southeast, a Kenyan military spokesman said Wednesday.

Col. Paul Njuguna also said 10 soldiers were wounded along the Kiunga-Sankuri road in Lamu County. Njuguna did not say in the statement who carried out the attack but suspicion has fallen on the al-Shabab extremist group from Somalia which the military was deployed to battle in that area. The soldiers were on a humanitarian mission to fetch and distribute water to the people of the area, Njuguna said.

Last month the military denied reports that six soldiers died from a roadside bomb in the same area. Al-Shabab has carried out a wave of attacks in Kenya as retribution for Kenya's 2011 deployment of troops to Somalia to fight the militants. More recently the extremist group has aimed its attacks on Kenyan security targets.

More than 100 police officers have been killed since May last year in al Shabab attacks. Kenya is among the six African countries that contribute troops to the Africa Union Mission in Somalia, known as AMISOM. Outside Somalia, Kenya has suffered the most al-Shabab attacks. AMISOM has bolstered Somalia's weak government against an al-Shabab insurgency.

The U.N. Security Council voted last month to delay the reduction of troops in the joint U.N.-African Union peacekeeping force in Somalia from October to February 2019 and its target date for Somali forces to take the lead in the country's security to December 2021.