The United States believes that Hamza bin Laden, a son of slain al-Qaeda leader Osama bin Laden and himself a notable figure in the militant group, is dead, a U.S. official said Wednesday.

The U.S. official, who spoke on condition of anonymity, provided no further details, including when Hamza died or where.

President Donald Trump earlier Wednesday declined to comment after NBC News first reported the U.S. assessment. Asked if he had intelligence that bin Laden's son had been killed, Trump told reporters: "I don't want to comment on it."

Separately, the White House declined comment on whether any announcement was imminent.

Hamza, born in 1989 and believed to be about 30 years old, was at his father's side in Afghanistan before the Sept. 11, 2001, attacks on the U.S. and spent time with him in Pakistan after the U.S.-led invasion of Afghanistan pushed much of al-Qaeda's senior leadership there, according to the Brookings Institution, a Washington-based think-tank.

Osama was killed by U.S. special forces who raided his compound in Pakistan in May 2011. Hamza was thought to be under house arrest in Iran at the time, and documents recovered from the compound indicated that aides had been trying to reunite him with his father.

The New York Times reported that the U.S. had a role in the operation that led to Hamza's death, which it said took place in the past two years. Reuters could not immediately verify those details.

Still, the U.S. government's conclusion appears to be a recent one. In February, the State Department said it was offering a reward of up to $1 million US for information leading "to the identification or location in any country" of Hamza, calling him a key al-Qaeda leader.

Supporters Osama bin Laden shout anti-American slogans, after the news of his death, during a rally in Quetta, Pakistan, on May 2, 2011. (Naseer Ahmed/Reuters)

'Global terrorist'

Introduced by al-Qaeda's chief Ayman al-Zawahiri in an audio message in 2015, Hamza provided a younger voice for the group whose aging leaders have struggled to inspire militants around the world galvanized by ISIS, according to analysts.

Hamza has called for acts of terrorism in Western capitals and threatened to take revenge against the U.S. for his father's killing, the U.S. State Department said in 2017 when it designated him as a "global terrorist."

He also threatened to target Americans abroad and urged tribal groups in Saudi Arabia to unite with Yemen's al-Qaeda in the Arabian Peninsula to fight against Saudi Arabia, it said.

In March, Saudi Arabia announced it had stripped Hamza of his citizenship, saying the decision was made by a royal order in November 2018.