The leader of al-Qaeda in the Arabian Peninsula, Nasser al-Wuhayshi, has vowed that imprisoned members of the armed network would be freed.
In a "letter to the captives in the tyrants' prisons" on Monday the head of al-Qaeda's Yemeni branch said "the detention (of the network's prisoners) cannot last".
"The imprisonment will not last and the chains will be broken," he said, adding that this would happen soon.
"Your brothers are about to bring down the walls and thrones of evil... and victory is within reach."
He added: "We're all on the same ship, some on the deck and others in the bunt and each team owes its survival to the other."
Wuhayshi, a former aide to al-Qaeda's late founder Osama bin Laden, tunnelled his way out of prison to become head of al-Qaeda in the Arabian Peninsula (AQAP) in 2007.
In July 2011, Wuhayshi pledged allegiance to Bin Laden's successor, Ayman al-Zawahiri.
His group, at the heart of the latest US security alert, has claimed responsibility for several attacks, including an attempt to blow up a US commercial airliner on Christmas Day 2009.
On Sunday an attack by "al-Qaeda elements" at a gas export terminal in Yemen killed five soldiers, a military source said, as Washington kept its embassy in Sanaa closed.
The attack followed a wave of US drone strikes against suspected al-Qaeda fighters in Yemen that has killed 38 people since July 28.
The United States said on Friday that all of the embassies it shut down due to the security alert would reopen this week, except the mission in Yemen.