ISLAMABAD (Reuters) - The Khyber Pass border between Pakistan and Afghanistan was closed to all traffic on Tuesday for the return of a Pakistani diplomat who was shot dead in Afghanistan by unknown gunmen.  Pakistan summoned the Afghan charge d affaires in Islamabad to protest against the killing of consular official Nayyar Iqbal Rana on Monday near his residence in the eastern city of Jalalabad, Pakistan s foreign office said in a statement. Relations between Afghanistan and Pakistan have been going through a stormy period with tensions over the latest U.S. strategic plan for the region and disputes over the Torkham border crossing, which Pakistan has closed periodically.   We received the body of late Nayyar Iqbal Rana in Torkham today,  a government official in Torkham who asked not to be identified told Reuters.   The Pakistan-Afghanistan border was closed for all types of traffic.  Afghanistan s ambassador to Pakistan, Omar Zakhilwal, condemned the killing in a message on Twitter and said he had conveyed his government s sympathies to the ministry of foreign affairs in Islamabad. The killing comes around a week after the deputy governor of Kunar province in eastern Afghanistan was kidnapped near the Pakistani city of Peshawar, although there was no immediate indication of any connection between the two. 