Residents said the militants launched a surprise attack and clashed with the local forces, known as popular committees. The militants then set up checkpoints at the entries to the towns and announced over loudspeakers after dawn prayers their takeover of both towns.
Jaar and Zinjibar, the capital of Abyan province, are about 50 km (30 miles) east of the main port city of Aden. They had fallen previously to militants from al Qaeda in the Arabian Peninsula in 2011.
At the time, the militants were emboldened by waning government control over the impoverished country during Arab Spring protests that eventually ousted former President Ali Abdullah Saleh.
The Yemeni army drove the militants out just over a year later.
This time, the country is convulsed in a protracted conflict that pits Shi’ite Houthi fighters and forces loyal to Saleh against a Saudi-led coalition and fighters loyal to President Abd-Rabbu Mansour Hadi.
Abdullatif al-Sayed, the head of Popular Committee fighters in Abyan province, said that he tried to repel the attacks and had informed officials what al Qaeda had been planning, but to no avail.
“The entrance of al Qaeda this time happened in the absence of any state institutions, which al Qaeda exploited,” said Zinjibar resident Fadl Mohammed Mubarak.