* Kaduna, Kano states attacked in organised raids
* Boko Haram commander declared ceasefire on Monday
KADUNA/KANO, Jan 31 (Reuters) - Gunmen killed at least five police in two attacks in northern Nigeria on Thursday, casting doubt on the ceasefire declared days earlier by a purported Islamist commander and highlighting how difficult it will be to end insecurity in the region.
Around 60 gunmen in the Birnin Gwari area of Kaduna state attacked the divisional police station and branches of Ecobank and First Bank with grenade launchers and assault rifles, killing three policemen, police said.
In a separate attack near the north's main city of Kano, suspected Islamists on motorbikes bombed a police station in Bunkure, burning it to the ground and killing two police.
Kaduna state Police Commissioner Olufemi Adenaike, who was at the scene of the Birnin Gwari attack, said a civilian was also killed in the coordinated raid.
"They overpowered the team of about 20 policemen," he said, declining to comment on whether this was an attack by Islamist sect Boko Haram or a criminal gang.
Local witnesses said they were sure the Islamists were behind the sophisticated attack.
A security source at Ecobank, who declined to be named, said the attackers had blown up the bank vault but could not gain entry to the safe.
Purported Boko Haram commander Sheik Abu Mohammed Ibn Abdulazeez declared a unilateral ceasefire on Monday, urging members to halt attacks that have killed hundreds since the sect launched an uprising against the government in 2009.
He claimed to be speaking on behalf of Boko Haram leader Abubakar Shekau, who neither publicly backed nor denounced the commander when he called for dialogue twice in November last year.
Doubts over the authority of Abdulazeez raise questions about possible rifts within the sect - analysts say Boko Haram has been broken up into smaller splinter groups by military pressure. The latest violence will deepen those doubts.
Even if Boko Haram was not behind these attacks, a number of criminal gangs operating in northern Nigeria have benefited from the insurgency, sometimes using the sect as cloak to hide behind.
Repairing this breakdown of law and order will be a tough task even if the Islamists do lay down their weapons.
On Wednesday, gunmen shot dead a security guard at the entrance to the university of Maiduguri, the northeastern city that forms Boko Haram's headquarters.
President Goodluck Jonathan has highlighted links between Boko Haram and Saharan Islamists as a reason for joining efforts by allied French and West African forces fighting them in Mali, but analysts say some kind of negotiated settlement may be his best chance of ending the insurgency on home soil. (Reporting by Isaac Abrak and Chukwuemeka Madu; Additional reporting by Ibrahim Mshelizza in Maiduguri; Writing by Tim Cocks; Editing by Sophie Hares)