Militants led by Aidarous Al-Zubaidi, head of the UAE-backed South Transitional Council, have increased their attacks on the Al-Islah party.
Al-Islah, with whom Al-Zubaidi has previously been aligned, ceased its alliance with the UAE's man in the south of Yemen following his rift with the internationally backed President Abd Rabbuh Mansur Hadi.
Al-Zubaidi's forces have escalated their attacks on Al-Islah since the Gulf blockade on Qatar began in early June. One of the reasons why the UAE, Saudi Arabia, Bahrain and Egypt claimed to have cut relations with Doha was its support for the "terrorist" Muslim Brotherhood group to which Al-Islah is affiliated.
Last week, the militias loyal to the UAE arrested 11 Al-Islah leaders, raided two of their headquarters and set one in fire.
Early this week, eight of the 11 leaders were released.
According to AlJazeera, Al-Islah is the main political party to oppose the rise of the Houthis and had tried to distance itself from the Muslim Brotherhood in an effort to ease Abu Dhabi's anxiety about its Islamist ideology.
The news organisation has reported that the UAE has operated a network of "black sites" in south Yemen where hundreds of men have been kidnapped by local militias. Local media reports claim some of those apprehended were members of Al-Islah.
Al-Islah's rejection of the south's secession, as per the UAE's plans, and desire to keep Yemen intact has made it a target for security forces.
The UAE entered the Yemen civil war as part of the Saudi-led coalition to support Yemen's President Hadi's governance in March 2015. Two years into the conflict, the Emirates supported the STC, which calls for secession from northern Yemen and Hadi's rule.