A candidate in the upcoming poll for a constituent assembly was murdered in Libya's southern desert on Sunday shortly after submitting his registration, a security official said. "Khaled Abu Saleh was murdered 30 kilometres (22 miles) from Ubari," in the south of Libya, Mohammed Saleh, deputy chairman of the High Security Commission, told AFP. "An armed gang traveling in five cars followed him after he registered with the electoral commission. They surrounded and killed him," the official said. The same source said "two people traveling with Khaled Abu Saleh in the car were able to flee," adding that an investigation was underway. An official of the High National Electoral Commission and a top security official confirmed the assassination without giving further details. A friend of the victim said Abu Saleh was on his way to his hometown of Murzak after registering as a candidate for the June elections. The ruling National Transitional Council has pledged to hold elections for a 200-seat constituent assembly by June 19. A total of 120 seats in the assembly are reserved for independent candidates, while the remaining 80 are open to political parties. More than 1.5 million Libyans have registered to vote in the June elections for the General National Congress, according to official figures. Flashes of violence, such as a deadly raid on government headquarters last week, have raised concerns over the capacity of authorities to secure the first election after decades of dictatorship under slain leader Moamer Kadhafi. Ethnic unrest in the south, calls for greater autonomy in the east and corruption are some of the challenges facing Libya's interim leaders. Since the start of the Arab Spring which also led to Kadhafi's fall last year, elections in the region have benefited Islamists, including in Egypt, Libya's neighbour to the east, and Tunisia to the west.