On Tuesday, dozens of people were rounded up by security forces, including three politicians from the Yemeni Socialist Party, in a crackdown on activists suspected of inciting protests in the provinces of Aden, Lahj and Dhaleh, witnesses said.
In a statement, the former ruling party in south Yemen confirmed the arrest of some party members and accused the government of seeking to "terrorise leaders of the peaceful protest movement".
However, the government alleges that "subversive elements" had engaged in "acts of sabotage and rioting" in southern provinces, "attacking innocent citizens and damaging public property".
Several protests have been held in southern Yemen in recent months to demand greater state aid for more than 60,000 people retired from the military and civil service, most of whom insist they were forced into early retirement.
Local residents often complain of discrimination since a 1994 southern secession bid, led by socialists, was crushed by northern forces loyal to Ali Abdullah Saleh, the president.