The area was the stronghold of interim president Ahmed al-Sharaa's Hayat Tahrir al-Sham group before it led the rebel offensive that toppled Bashar al-Assad in December.

"US Central Command forces conducted a precision air strike in northwest Syria targeting and killing Muhammad Salah al-Zabir, a senior operative in the terrorist organisation Hurras al-Din, an Al-Qaeda affiliate," CENTCOM said in a statement.

Britain based-war monitor the Syrian Observatory for Human Rights said Zabir was killed when the vehicle he was travelling in on the Sarmada-Idlib road was hit by a US drone strike.

The US strike came days after Hurras al-Din announced its dissolution in line with orders from the interim president.

The Observatory said Hurras al-Din "announced its dissolution so as not to enter into armed conflict with HTS."

Sharaa's faction was Al-Qaeda's Syria affiliate until it broke ties with the jihadist network in 2016.

The US-based SITE Intelligence Group said Hurras al-Din was founded in February 2018.

It did not publicly confirm its allegiance to Al-Qaeda until its dissolution announcement on Tuesday.

The United States designated Hurras al-Din as a "terrorist" organisation in 2019 and has offered financial rewards for information on several of its members.

It carried out successive air strikes targeting the group's leadership in northwestern Syria in August and September last year.

Washington also still blacklists HTS as a "terrorist" group, although it has lifted some of its sanctions against Sharaa's group since it toppled Assad last year.