* Boko Haram insurgency spreading in the north
* Sect is President Goodluck Jonathan's top security woe (Adds new attack, details)
MAIDUGURI, Nigeria, March 13 (Reuters) - At least seven people were killed in separate attacks by suspected Islamist militants targeting security patrols in northern Nigeria on Tuesday, police said.
Gunmen on motorbikes opened fire on a joint army and police patrol in the remote northeast Nigerian town of Mubi overnight, killing two security officials and three civilians, police said.
Later on Tuesday, gunmen in the north's biggest city of Kano ambushed a joint military and police patrol, triggering a gun battle in which two policemen were killed, the military said. One of the suspected militants also died in the battle.
Police spokesman Altine Daniel said security had been boosted in the town since the attack in Mubi.
The gunmen's identities were not known, although suspicion is likely to fall on Islamist sect Boko Haram, which is waging an increasingly violent insurgency against Nigeria's government in the north that has mostly targeted security forces.
"A total of five people were shot dead by unknown gunmen. they include one soldier, one policeman who was not on duty and three other civilians that were hit by stray bullets," Daniel said. "Three soldiers also sustained serious injuries."
Kano army spokesman Iweha Ikedichi confirmed the attack in Kano. Suspected Boko Haram militants also struck a police station near the city on Monday, wounding two policemen in a drive-by shooting, police said.
The insurgency has grown in sophistication in the past six months, and expanded its range of targets to include Christians, posing a major headache for President Goodluck Jonathan, who has been criticised to failing to quell it.
Boko Haram has claimed responsibility for a spate of bombings against churches since Christmas Day, including several in Jos, a city prone to sectarian conflict between Christian and Muslim communities, which the bombs seem targeted to inflame.
Christian youths killed at least 10 people in reprisal attacks after a suspected suicide bomber hit a Catholic church in the central Nigerian city of Jos on Sunday, killing three people, and the military was called in to quell rioting during which it shot and wounded some youths, authorities said.
(Reporting by Ibrahim Mshelizza; Additional reporting by Bala Adamu in Kano; Writing by Tim Cocks; Editing by Karolina Tagaris)
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