At least 62 prisoners suspected of belonging to al-Qaeda escaped from a prison in the southern Yemeni city of Mukalla on Wednesday, local media reported.
At least one policeman was killed in the breakout, the independent Yemen Post reported.
Activists have accused President Ali Abdullah Saleh and his government of "handing over" parts of southern Yemen to the terrorist network, in a bid to garner international support for Saleh to stay in power despite mass protests calling for his ouster, dpa reported.
The embattled president is currently in hospital in neighbouring Saudi Arabia, recovering from injuries sustained during an attack on his presidential palace in the capital Sana'a earlier this month.
US Assistant Secretary for Near Eastern Affairs was in Yemen on Wednesday for talks with foreign minister Abubakr al-Qirbi and Saleh's deputy Abd-Rabbu Mansour Hadi, who is acting president.
He is also due to hold talks with Saleh's son, Ahmed Ali Abdullah Saleh.
Protesters in Yemen are demanding that Saleh makes his exile permanent, and are calling for the formation of a transitional council.
But government officials have said that Saleh would return "soon." In the meantime, it is not clear who is in charge and clashes between protesters, Saleh's supporters, and security forces continue to erupt in southern Yemen.
Saleh, a US ally in the war on terror, has been in power for over 32 years. Violence recently escalated in Yemen when he refused, for the third time, to sign a power transfer agreement after months of widespread protests