KANO, Nigeria - Nigerian authorities said on Thursday they had arrested three Lebanese in northern Nigeria on suspicion of being members of Hezbollah and that a raid on one of their residences had revealed a stash of heavy weapons.The three suspects were arrested between May 16 and May 28 in the north's biggest city Kano, the city's military spokesman Captain Ikedichi Iweha said in a statement. All had admitted to being members of Hezbollah under questioning.Weapons stashThe third, Talal Roda, a Nigerian and Lebanese citizen, was arrested on Sunday at the house where the weapons were found two days later."The search team uncovered an underground bunker in the master bedroom where a large quantity of assorted weapons of different types and caliber were recovered," Iweha said. "All those arrested have confessed to have undergone Hezbollah terrorist training." The possibility of a link with Nigerian Islamist sect Boko Haram, which Nigerian forces are battling in a major offensive in the northeast, was being investigated, Iweha said at a news conference.An alliance between Salafist Sunni Muslim Boko Haram and Shi'ite Hezbollah would be unusual, and there has never previously been evidence of such a link.Though most Nigerian Muslims are Sunni, there are several thousand Shi'ite Nigerians, a legacy of Muslim radical Ibrahim Zakzaky's preachings since the 1980s. Zakzaky still leads Nigeria's main Shi'ite movement and has campaigned for an Islamic government and stricter adherence to sharia law.Iweha declined to say if any link to Zakzaky was being investigated, and his movement is currently seen as largely peaceful.A Nigerian court sentenced an alleged member of Iran's Revolutionary Guard and a Nigerian accomplice to five years in prison this month over an illegal shipment of mortars and rockets seized in the main port of Lagos in 2010.A raid on the residence of one of the Lebanese had uncovered 11 60 mm anti-tank weapons, four anti-tank landmines, two rounds of ammunition for a 122 mm artillery gun, 21 rocket-propelled grenades, seventeen AK-47s with more than 11,000 bullets and some dynamite, he said."The arms and ammunition were targeted at facilities of Israel and Western interest in Nigeria," Iweha said, but did not elaborate.Separately, five fighters from Chad and two from Niger were arrested among insurgents fleeing a two-week-old offensive against Islamist sect Boko Haram in the northeast, as they tried to cross the border into Chad, Nigeria's defence spokesman Brigadier General Chris Olukolade said in a statement.Authorities believe there has been a growing involvement of al-Qaeda-linked foreign jihadists in Nigeria's insurgency.The secret service detained the first suspect, Mustapha Fawaz, on May 16 at his supermarket in Kano. His interrogation led to other suspects, including Abdullah Tahini, who was later arrested at Kano airport with $60,000 in undeclared cash.