In northern Nigeria troops have traded fire with Islamic militants surrounding the suspected hideout of a radical Muslim leader accused of orchestrating a campaign of violence which has claimed the lives of scores of people.The followers of Mohammed Yusuf’s Boko Haram sect barricaded themselves into the house after clashes with soldiers sent to contain the fighting. Nigerian President Umaru Yar’Adua said the fighting was now under control and appealed for calm. Boko Haram is being blamed for violent attacks across four of Nigeria’s northern states since Sunday. The group says Nigeria’s government is being corrupted by the West and wants Islamic law to be established throughout the country. In the Wudil district of Kano state, where militants attacked a police station on Monday, 17 people were arrested overnight, bringing the total detained there to 53.