By Michelle Nichols
UNITED NATIONS, July 2 (Reuters) - South Sudanese government security officers prevented several local U.N. staff from traveling to Uganda this week in two incidents believed to based on their ethnicity, U.N. officials said on Wednesday.
South Sudan has been in political turmoil since President Salva Kiir sacked his deputy Riek Machar last year, triggering a conflict that has reopened deep ethnic tensions in the world's youngest country which only won independence from Sudan in 2011.
Kiir comes from the dominant Dinka ethnic group, while Machar, now rebel leader, is from another major tribe, the Nuer.
U.N. spokesman Stephane Dujarric said that four national U.N. staff were denied permission to board a U.N. plane on Monday by National Security officers from the government of South Sudan and their passports were confiscated.
"It's unfortunately not an isolated incident," Dujarric told reporters. "A similar incident occurred with two other UNMISS national staff members at the airport yesterday."
UNMISS is the U.N. peacekeeping mission in South Sudan. U.N. officials, speaking on condition of anonymity, said that the staff in both incidents were targeted based on their ethnicity.
Dujarric said the U.N. staff members were traveling to Entebbe for official training at a regional support center.
"UNMISS was not given any legal explanation or other reason for barring their official travel. The mission therefore asked the authorities to return their travel documents and allow their official travel," he said.
South Sudanese authorities returned the passports and UNMISS identification cards to the U.N. mission earlier on Wednesday.
The fighting in South Sudan erupted in mid-December after months of political tensions sparked by the sacking of Machar. Thousands have died in the conflict and more than 1.3 million people have been driven from their homes.
The U.N. Security Council almost doubled the mandated number of peacekeepers in late December to 12,500 troops and 1,323 police, but so far only some 8,100 troops are on the ground. (Reporting by Michelle Nichols; Editing by Cynthia Osterman)