NAIROBI, Feb. 23 (Xinhua) -- Kenyan police on Friday launched a major manhunt for an al-Shabaab commander and five other key terror suspects behind a series of attacks in northeastern Kenya.

The police have offered 20,000 U.S. dollars each for any information that could lead to the arrest of the six suspected al-Shabaab militants believed to be planning terror attacks in the east African nation

Authorities have circulated a photo of a woman and five men, including Issack Alio Mohammed, a Kenyan al-Shabaab commander and an improvised explosive device (IED) expert.

Other terror suspects being sought by the police include Abdiwhab Osman, Hareth Hillow, Kusow Yarrow and Mumina Erobe.

Alio, an al-Shabaab operative who hails from Mandera County in northeast Kenya, is believed to be behind a series of attacks along the Somalia border.

His main targets have been security personnel and telecom cell towers in Kenya's northeast and coastal regions.

The police called on the public to be vigilant and report the whereabouts of the suspects.

Kenya faces insecurity as bomb attacks using IEDs and grenades have become more frequent in the northeastern and coastal regions since its soldiers entered Somalia in 2011 to fight al-Shabaab and secure the shared border.