Two spies allegedly working for the US were gunned down at two different places in the Pakistani tribal agency of North Waziristan along Afghan border on Wednesday by suspected Taliban militants, said officials. Militants killed a local doctor in Saobi village of Miramshah, the regional Headquarters, and an Afghan national was shot to death in Mir Ali district of Miramshah, security officials told KUNA. They said militants also left letters near their bodies warning tribesmen of the same fate if found spying for Americans. Militants often kill tribesmen suspected of working for Pakistani and US security forces in North Waziristan but authorities so far have been unable to capture any of those responsible.