KALAYA, Pakistan - At least 20 militants and five soldiers were killed when Pakistani forces and a group of militants clashed in northwestern Pakistan on Tuesday, military officials said.The skirmish, which took place in the Ghaljo area of the northwestern Orakzai tribal region, began when militants ambushed a Pakistani military patrol.Officials said 18 soldiers were wounded in the ambush; however, the death toll could not be independently verified, and militants often dispute official figures.Several militant groups are active in Pakistan's northwestern semi-autonomous tribal regions, near the border with Afghanistan, including the Pakistan Taliban, responsible for many of the bombings across the country in recent years.