Nigeria's army said on Sunday it discovered an arms cache in the northern city of Maiduguri, the bastion of Islamist group Boko Haram. The cache houses anti-aircraft guns, bombs and rockets in addition to military uniforms which they were planning to manipulate to foil Nigerian President Goodluck Jonathan's visit to the city on Friday, the army said in a statement. The army spokesman, Lt Colonel Sagir Musa, said it launched the operation after receiving a tip that Boko Haram was orchestrating an operation in the city to thwart the president's visit, the first since the 2011 elections. The army said in a statement Saturday that two of its soldiers and 52 gunmen were killed during an operation launched against armed men in Maiduguri over the past days. Seventy armed men were rounded up during the operation.