Pakistani security forces Wednesday in an operation arrested four suspected militants and seized huge cache of arms and ammunition in South Waziristan tribal agency, bordering Afghanistan, a day after two roadside bombs killed a soldier and a tribal elder in the area, said officials. About a hundred troops backed by gunship helicopters swoop Shakai area today and arrested four local suspected militants, security officials told KUNA.They said that they arrested huge cache of arms and ammunition including bomb-making explosive material. The operation was conducted a day after two roadside bombs, being planted by suspected Islamic militants, in the area killed a soldier and tribal elder. Explosions also wounded five soldiers and three tribal elders. Pakistani military officials believe that scores of al-Qaeda suspects are hiding in the tribal region. These militants had fled Afghanistan during US-led military operations. Pakistan has deployed over 80,000 troops along its border with Afghanistan to check cross-border-movement.