ISLAMABAD (AFP) - Security forces killed 11 militants and wounded nine in raids against extremist strongholds in the Swat Valley on Thursday, security officials said. It was impossible to confirm the statistics from independent sources. Security forces said the casualties occurred in operations on Wednesday in the hamlets of Qambar, in Mingora district, and Kuza Duresh Khela, in Matta district. More than 1,500 soldiers have been killed at the hands of extremists since 2002, after the Islamabad government joined the so-called war on terror declared by former US president George W Bush. Pakistan rejects Western accusations that it is not doing enough to tackle the extremist threat on its soil, where a wave of spectacular fundamentalist attacks have killed more than 1,500 people in 17 months. Our Monitoring Desk adds: four civilians were killed and eight others injured when security forces' gunship helicopters targeted in a factory in Swat, reported BBC on Thursday. Meanwhile, unknown miscreants blew up another girls' school with explosive material at Qambar area of Mingora city during the night between Wednesday and Thursday, police said. Consequently, the building of the school was completely destroyed while the total number of destroyed schools climbs to 184 in the district out of which 169 were girls' schools. Meanwhile, unknown saboteurs blew up a woolen factory with explosives in Rehmanabad area of Mingora City, which destroyed a large part of the factory. However, no human causality was reported in the incident.