They said on Saturday that the clashes, which erupted in Taiz a day earlier, saw a faction financed and armed by the United Arab Emirates and led by Salafi commander Aboul Abbas, confront other factions affiliated with the Muslim Brotherhood group in Yemen - the Islah party - which is loyal to Yemeni president Abed Rabbo Mansour Hadi.
They spoke on condition of anonymity because they were not authorized to brief media.
The violence in Taiz underscores the deep divisions marring allies in Yemen's war which pits the internationally recognized government backed by a Saudi-led coalition against Iran-backed Shiite rebels.
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