The leader of the Islamic State sought to rally his backers in an audio statement released on Thursday, just days after Iraqi officials said the militant chief was injured in U.S. airstrikes.

It was unclear whether the defiant recording by Abu Bakr al-Baghdadi — urging followers to unleash “volcanoes of jihad” — was made before or after the airstrikes last Friday.

The United States said this week that it could not confirm whether the elusive Baghdadi was killed or wounded in any of the attacks targeting the ­Islamic State leadership in northern and western parts of Iraq.

It was not clear when the
audio recording was made, but ­Baghdadi referred to President Obama’s decision Nov. 7 to double the U.S. troop deployment in Iraq to nearly 3,000. On Tuesday, 50 U.S. military personnel arrived at Iraq’s al-Asad Air Base in Anbar province, the U.S. Central Command said.

In the recording, the Islamic State leader mocked the United States for again sending ground troops “to their death and destruction” in Iraq. He vowed that Islamic State militants would fight to the last man.

U.S. and allied warplanes have carried out hundreds of airstrikes against the militants in Iraq and Syria since the offensive started in August. But the fighters continue to hold large swaths of territory.

Baghdadi heaped scorn on the U.S.-led coalition for its campaign of “fear, weakness . . . and failure” against the Islamic State.

The coalition’s “airstrikes and constant bombardment — day and night — upon the positions of the Islamic State have not prevented its advance, nor weakened its resolve,” Baghdadi said in the 17-minute audio message.

The recording was released online by the Islamic State’s official media arm, al-Furqan Media. It appeared authentic, and the voice corresponded with previous recordings of Baghdadi released by the group, the Associated Press reported.

“When he was reported injured, I said: ‘By the end of the week, we will either have a new speech [from Baghdadi] or a
new caliph,’” said Hisham al-Hashemi, an Iraqi researcher and expert on the Islamic State.

Baghdadi declared himself
or leader, of the Islamic State from the northern Iraqi city of Mosul in June. The group’s de facto capital is Raqqah, Syria. But Baghdadi is an Iraqi national and spent 10 months in a U.S. detention center in this country in 2004.

In the message released Thursday, he also noted recent claims of allegiance from other militant factions in Egypt, Libya and elsewhere. He called for followers to “draw your swords” against Saudi Arabia, where at least eight people were killed
last week in an attack at a gathering of the kingdom’s minority ­Shiites.

The Sunni-led Islamic State considers Shiites a heretical branch of the faith and ­condemns Saudi Arabia and ­others for their alliance with the West.

“O soldiers of the Islamic State . . . erupt volcanoes of jihad ­everywhere. Light the earth with fire against all dictators,” Baghdadi said.

“He sounded healthy,” the ­researcher Hashemi said.

In Washington, Army Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff, raised the possibility of further “modest” increases in the number of U.S. soldiers sent to Iraq, saying they could be dispatched to places such as Mosul or territory along the Syrian border.

“I’m not predicting at this point that I would recommend that those [Iraqi] forces in Mosul and along the border would need to be accompanied by U.S. forces, but we’re certainly considering it,” Dempsey told the House Armed Services Committee.

Mustafa Salim in Baghdad and Brian Murphy in Washington contributed to this report.