NAIROBI (Reuters) - Kenya has seized six men suspected of planning an attack sponsored by the al Shabaab militant group from neighboring Somalia, the head of Kenyan police said late on Sunday.

In recent weeks, the East African nation has lost 20 officers in various attacks, mostly on deserted roads in the vast northern region bordering Somalia, in which the militants used Improvised Explosive Devices (IEDs).

Joseph Boinnet, the inspector general of the police, said in a statement that two of the suspects were Kenyans and the others were Somali nationals. Police also seized assembled explosives, four suicide vests and bomb-making materials such as TNT.

“The six had been dispatched from Burhanche in Somalia by their commanders to launch attacks in Kenya,” Boinnet said.

Kenyan security forces worked with their counterparts in Somalia to foil the attack and to capture the suspects. The captured men were being interrogated to establish the extent of the entire network, Boinnet said.

Kenya has faced a constant security challenge from across the border ever since it sent its troops into Somalia in late 2011, to help defeat the al Shabaab militants and restore order.