SANA, Yemen — A top Al Qaeda leader in Yemen blamed President Obama Thursday for the deaths last week of an American and a South African hostage in a failed US rescue operation.

The video message by Nasr bin Ali al-Ansi, posted on one of the militant group’s Twitter accounts, was the first comment by Al Qaeda’s Yemeni branch on the killings of Luke Somers and Pierre Korkie.

The two were killed when US special forces attacked an Al Qaeda safe house while trying to rescue Somers, an American photojournalist. Officials said US forces did not know that he and Korkie, a South African teacher, were being held together.

About 40 US special operations forces, backed by Yemeni ground forces, were involved in the half-hour rescue attempt in Shabwa province, which followed US drone strikes in the area east of the capital of Sana, US officials said. After a firefight with militants, the rescuers eventually reached the men and found them alive but gravely wounded. They both died soon after as medics tried to save them.

Ansi said he warned the United States against such attempts after the first rescue attempt in November also failed. He accused Obama of recklessness, and said the raid ‘‘caused things to go in a completely different way than we wanted.’’

Obama said he ordered the raid because the 33-year-old Somers was believed to be in ‘‘imminent danger.’’ The president condemned his killing as a ‘‘barbaric murder.’’

Ansi described the rescue operation as an ‘‘execution order’’ and claimed that poorly equipped militants fended off heavily armed US forces for nearly three hours.

Initial Al Qaeda demands were never clear. Ansi claimed Thursday that the group wanted to negotiate the release of detainees at Guantanamo Bay. He also mentioned Sheik Omar Abdel-Rahman, known as the Blind Sheik, who is serving a life sentence in the United States on a terrorism conviction.

‘‘They could have at least negotiated with us about some clauses or shown sincerity,’’ he added.

Ansi also warned that Al Queda will continue to ‘‘put the lives of all Americans in danger inside and outside of America . . . in the air, on the ground, and in the sea.’’

Washington considers Al Qaeda in the Arabian Peninsula, as the Yemeni branch is officially known, to be the most dangerous affiliate of the terrorist group founded by Osama bin Laden. The group has been linked to several sophisticated plots to attack the United States that were botched or foiled.

With the permission of Yemen’s government, the United States has for years launched drone strikes against militant targets there and provided Yemen with hundreds of millions of dollars in security assistance. Civilian casualties from the drone strikes have stoked anger.

Hours before the release of the video, the Al Qaeda affiliate said it shelled a Yemeni air base used by US forces.

It was not immediately clear whether there were casualties at the Al-Annad base early Thursday in the southern province of Lahj. Ambulances rushed to the site and witnesses say they saw bodies taken to a nearby hospital.