Militants have expanded their operations in southern Yemen during months of turmoil which paralyzed the country and eventually unseated former President Ali Abdullah Saleh, who was replaced in a February vote by Abd-Rabbu Mansour Hadi.
Local residents in Jaar, a southern town seized by militants in March last year, said Yemen's air force had killed 20 al Qaeda-linked fighters at a military base they had snatched from the government last week.
However, a spokesman for Ansar al-Sharia (Partisans of Islamic Law) denied its fighters were killed in the raid, which also destroyed weapons and military equipment.