The man mixed in with a group of recruits as they headed to their base in the southern city which serves as a temporary capital for the government, the official said.
Army and government installations have been the target of several attacks by extremists since pro-government forces drove out Shia rebels in the summer.
Al Qaeda and the Islamic State group have taken advantage of the chaos caused by the war between the government and the rebels to strengthen their grip on southern Yemen.
But after having long ignored them, forces loyal to President Abedrabbo Mansour Hadi have launched operations against them in the past few weeks, backed by the firepower of a Saudi-led military coalition.
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