* Boko Haram a major security headache for Jonathan
* Sect has infiltrated Kano, Nigeria's second-largest city (Adds arrests, weapons seizures, paragraphs 9-11)
KANO, Nigeria, March 9 (Reuters) - A gun battle broke out on Friday between suspected Islamist militants and police in Nigeria's biggest northern city of Kano, after gunmen opened fire on a police station, a police spokesman said.
At least three police officers were wounded in the attack, spokesman Ibrahim Idris said, adding the area had since been cordoned off.
"There was an attack on the police station but we were able to repel them. It is a big area so we can't say anything yet on the casualties," he said.
The Boko Haram Islamist sect, which is based in the north and styles itself on the Taliban, is waging a low-level insurgency against the southern-dominated government, proving a growing security headache for President Goodluck Jonathan.
The group has been blamed for almost daily shootings and bombings that have killed hundreds of people in the past two years. A Briton and an Italian held hostage in Nigeria were killed by their captors on Thursday, after being held for almost a year by what security officials said was a Boko Haram faction.
Security officials say the group has received some training, weapons and bomb-making technology from al Qaeda in the Islamic Magreb, which operates in neighbouring Niger and Chad.
The militant group is fighting to impose Islamic Sharia law in a country split between Christians and Muslims.
Suspected Boko Haram insurgents attacked a police station and two banks in a remote part of the northeast on Thursday, killing seven people.
The military said they arrested three suspected Boko Haram militants and seized a weapons cache near the group's northeastern heartland of Maiduguri on Friday.
The weapons seized included eight Ak-47 assault rifles, bomb making materials, pistols and hundreds of rounds of ammunition.
"All these weapons were recovered in Dala ward with the assistance of the three sect members who gave us the information on the different locations," said spokesman for the Joint Task Force in Maiduguri, Lieutenent Colonel Hassan Mohammed.
The Islamists used to be confined to the northeastern heartland of Maiduguri, but have in the past six months radiated across the north and struck the capital a handful of times.
They have moved heavily into Kano, a city of more than five million, where they carried out their most lethal strike to date in January, setting off bombs and gun battles that killed at least 186 people, most of them civilians.
On a visit to Nigeria on Monday, U.S. Under Secretary for Political Affairs Wendy Sherman urged the government to tackle the Islamist insurgency by bringing jobs and development to the deprived region, and pledged to support Abuja in the task. (Reporting by Bala Adamu in Kano and Ibrahim Mshelizza in Maiduguri; Writing by Tim Cocks; Editing by Sophie Hares)